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Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The analysis of collaborative contribution networks and hot spots in earthquake research from a global perspective will reveal some rules and trends in this field that will provide references and macroguidance for scientific researchers in the field. With the help of data analysis software Excel and visualization software VOSviewer, this study mainly uses two methods of bibliometric and social network analysis to analyze 66,296 papers on the subject of "earthquake" collecting in Web of Science in 2009–2018 from multiple perspectives. In the past 10 years, scientific research output in the earthquake field has steadily increased year by year with an evident cross subject. The contribution of co-publishing is much higher than that of single publishing, and it has a higher number of citations and displays. Half of the 50 keywords with the highest frequency of co-occurrence are the continuation of hot spots in 1900–2010. The evolution of hot spots shows that in the average publishing year of 2013.5–2015.0, hot spots have changed from old to new, but few new hot spots have appeared in the past 2 years. [ABSTRACT FROM AUTHOR]

Simple Summary: A bibliometric analysis of studies on the topic of earthworm in the soil ecosystem was conducted to reveal the research advances and trends in the field. The ecological effects of earthworms, the impact of agricultural activities on earthworms, earthworm ecotoxicology and earthworm invasion were four research hotspots on the topic and "impact", ''biodiversity", "oxidative stress", "diversity", "response", "Eisenia fetida" and "exposure" have been the emerging active topics. The earthworm, as a soil engineer, plays highly important roles in the soil ecosystem for shaping soil structure, promoting soil fertility, regulating microbial community composition and activities and decomposing soil pollutants. However, the research progresses on this important soil fauna have rarely been reviewed so far. Therefore, we conducted a bibliometric analysis of the literature published during 1900–2022, which was collected from the Web of Science Core Collection (WoS). The results showed that three periods (1900–1990, 1991–2005 and 2006–2022) could be identified in terms of the intensity of publications on the topic, and the number of publications kept increasing since 2006. The United States produced the highest publication record at the country scale, whereas Chinese Academy of Sciences was the most productive institution. Chinese institutions and authors played an active and prominent role during 2018–2022. Soil Biology & Biochemistry was the most popular journal for the topic-related research. In these publications, Professor Lavelle P was the most influential author. Based on a citation network of the top 50 cited papers, four hotspots were identified, i.e., the ecological effects of earthworms, the impact of agricultural activities on earthworms, earthworm ecotoxicology and earthworm invasion. Moreover, "impact", "biodiversity", "oxidative stress", "diversity", "response", "Eisenia fetida" and "exposure" were the emerging and active topics in recent years. This study can help us to better understand the relevant subject categories, journals, countries, institutions, authors and articles and identify the research hotspots and emerging trends in the field of soil earthworm research. [ABSTRACT FROM AUTHOR]

Creep is recognised to be an important physical property of soils, exerting a profound influence on the stability of structures. In order to gain a comprehensive understanding of the advancements and focal points in soil creep research, the relevant literature was accessed from the Web of Science Core Collection database, totalling 3907 papers (as of 25 March 2024). Statistical analyses on publication volume, keyword co-occurrence, and clustering were conducted using the visualization software VOSviewer (1.6.20). The current hotspots in soil creep research were identified, and a systematic review was undertaken on the influencing factors of soil creep and the corrective methods of creep models. The research findings indicate that the number of papers on creep research exhibits a trend of increase followed by a decrease over time. Developed countries, such as those in Europe and America, initiated research in this field earlier than developing countries like China. Currently, the research focus is primarily centred on creep models. Significant differences exist in the creep deformation of soils under different influencing factors, with soil microstructure, moisture content, and stress path being important factors affecting soil creep deformation. Creep deformation in unsaturated soils primarily considers the influence of matric suction, while indoor creep tests are mainly conducted based on vertical loading, which differs significantly from the stress conditions experienced by soils in engineering construction sites. Currently, adjustments to soil parameters are mainly made through single-factor adjustments involving stress, time, damage, and matric suction to determine creep models under specific influencing factors, and then to modify the models accordingly. However, research on the creep deformation mechanism and creep models under multiple factors is relatively limited. Future research directions are expected to focus on the microscopic scale of creep mechanisms and multi-factor creep models. [ABSTRACT FROM AUTHOR]

The article discusses the "Bring and Share" sessions at the British Earth Science Teachers' Association (ESTA) 2013 Annual Conference held in Plymouth, England. Presentations discussed include Peter Kennett, Elizabeth Devon, and Chris King on preparation for outdoor geology fieldwork, Pete Loader on the use of toilet paper in teaching Earth structure, and Chris Bedford on modelling hotspot formations.

Coastal peatlands in Southeast Asia release large amounts of organic carbon to rivers, which transport it further to the adjacent estuaries. However, little is known about the fate of this terrestrial material in the coastal ocean. Although Southeast Asia is, by area, considered a hotspot of estuarine CO2 emissions, studies in this region are very scarce. We measured dissolved and particulate organic carbon, carbon dioxide (CO2) partial pressure and carbon monoxide (CO) concentrations in two tropical estuaries in Sarawak, Malaysia, whose coastal area is covered by peatlands. We surveyed the estuaries of the rivers Lupar and Saribas during the wet and dry season, respectively. The spatial distribution and the carbon-to-nitrogen ratios of dissolved organic matter (DOM) suggest that peat-draining rivers convey terrestrial organic carbon to the estuaries. We found evidence that a large fraction of this carbon is respired. The median pCO2 in the estuaries ranged between 618 and 5064 μatm with little seasonal variation. CO2 fluxes were determined with a floating chamber and estimated to amount to 14-272molm-2 yr-1, which is high compared to other studies from tropical and subtropical sites. In contrast, CO concentrations and fluxes were relatively moderate (0.3- 1.4 nmol L-1 and 0.8-1.9 mmolm-2 yr-1) if compared to published data for oceanic or upwelling systems. We attributed this to the large amounts of suspended matter (4- 5004mgL-1), limiting the light penetration depth. However, the diurnal variation of CO suggests that it is photochemically produced, implying that photodegradation might play a role for the removal of DOM from the estuary as well. We concluded that unlike smaller peat-draining tributaries, which tend to transport most carbon downstream, estuaries in this region function as an effcient filter for organic carbon and release large amounts of CO2 to the atmosphere. The Lupar and Saribas mid-estuaries re25 lease 0.4±0.2 TgCyr-1, which corresponds to approximately 80% of the emissions from the aquatic systems in these two catchments. [ABSTRACT FROM AUTHOR]

Scholars have done a lot of research on urban settlement, but it is difficult to give consideration to the temporal and spatial attributes of settlement at the same time in its display and analysis. Most of them focused on the analysis of regional settlement, single point settlement curve and settlement rate map at a certain time, but few combined time and space for collaborative analysis. Therefore, in this paper, 32 scenes Sentinel-1B SAR data are used to obtain settlement data of Beijing via PS-InSAR method. Secondly, combined with the temporal and spatial attributes of settlement results, the subsidence law revealed by using spatio-temporal cube slicing and attribute filtering. Finally, subsidence development trend and the detection of abnormal subsidence are explored by emerging hot spots (ESH) analysis. The experimental results show that the settlement funnel center in Beijing is mainly concentrated near the junction of Chaoyang district and Tongzhou district. The settlement range tends to expand. There are several local continuous subsidence areas in the settlement oscillating area. Spatio-temporal analysis makes the development trend of urban settlement more intuitive. Emerging hotspot analysis combined with Getis-Ord Gi* statistics and Mann-Kendall trend test could more effectively analyze the settlement trend of the study area and detect new potential settlement centers, so that to provide auxiliary decision-making for urban safety early warning and city development. [ABSTRACT FROM AUTHOR]

Small-scale surface heterogeneities can influence land-atmosphere fluxes and therefore carbon, water and energy budgets on larger scale. This effect is of particular relevance for high-latitude ecosystems, because of the great amount of carbon stored in their soils. We introduce a novel micro-topographic model, the Hummock-Hollow (HH) model, which explicitly represents small-scale surface elevation changes. By computing the water table at the small scale, and by coupling the model with a process-based model for soil methane processes, we are able to model effects of micro-topography on hydrology and methane emissions in a typical boreal peatland. In order to assess the effect of micro-topography on water balance and methane emissions of the peatland we compare two versions of the model, one with a representation of micro-topography and a classical single-bucket model version, and show that the temporal variability in the model version with micro-topography performs better if compared with local data. Accounting for micro-topography almost triples the cumulative methane flux over the simulated time-slice. We found that the single-bucket model underestimates methane emissions because of its poor performance in representing hydrological dynamics. The HH model with micro-topography captures the spatial dynamics of water and methane fluxes, being able to identify the hotspots for methane emissions. The model also identifies a critical scale (0.01 km²) which marks the minimal resolution for the explicit representation of micro-topography in larger-scale models. [ABSTRACT FROM AUTHOR]

We analysed mooring and ship-based hydrographic and biogeochemical data obtained from a Hope Valley biological hotspot in the southern Chukchi Sea. The moorings were deployed from 16 July 2012 to 19 July 2014, and data were captured during spring and fall blooms with high chlorophyll a concentrations. Turbidity increased and dissolved oxygen decreased in the bottom water at the mooring site before the fall bloom, suggesting an accumulation of particulate organic matter and its decomposition (nutrient regeneration) at the bottom. This event may have been a trigger for the fall bloom at this site. The bloom was maintained for 1 month in 2012 and for 2 months in 2013. The maintenance mechanism for the fall bloom was also studied by hydrographic and biogeochemical surveys in late summer to fall 2012 and 2013. Nutrient-rich water from the Bering Sea supplied nutrients to Hope Valley, although a reduction in nutrients may have occurred in 2012 by mixing of lower-nutrient water that would have remained on the Chukchi Sea shelf during the spring and fall blooms. In addition, nutrient regener ation at the bottom of Hope Valley could have increased nutrient concentrations and explained 60% of its nutrient content in fall 2012. The high nutrient content with the dome-like structure of the bottom water may have maintained the high primary productivity at this site during the fall bloom. Primary productivity was 0.3 in September 2012 and 1.6 gCm-2 d-1 in September 2013. The lower productivity in 2012 was related to strong stratification caused by the high fraction of surface sea ice meltwater. [ABSTRACT FROM AUTHOR]

Since the world became industrialized, our environment has been changed, bringing different environmental issues. The world benefits from industrialization but suffers from diverse pollutions simultaneously. Therefore, we are motivated to investigate the environment and landscape management explorations by analyzing 403 papers published in the Journal of Environmental Engineering and Landscape Management (JEELM) from 2007 to 2019. As one of the scientific journals that investigate environment management, JEELM mainly focuses on the area of environmental changes caused by human activities. By analyzing the issues such as atmosphere, water, and soil pollution and their mitigation technologies, JEELM accepts the scientific outputs written in English. Based on the data retrieved from Web of Science, we provide an overview of the status quo and emerging trends of the researches published on JEELM. Diverse researches such as publication distribution, citation structure, co-citation analysis and key contributors on the aspects of countries, institutions, and authors are given to comprehensively analyze the current situation of JEELM's. Besides, the emerging trends and hot spots can be revealed by burst detection and timeline view. Therefore, this paper contributes to providing a general picture of the knowledge domain of JEELM' research which enables researchers, especially the beginners to learn about this journal's development. [ABSTRACT FROM AUTHOR]

Drained peatlands are significant hotspots of carbon dioxide (CCO2) emissions and may also be more vulnerable to fire with its associated gaseous emissions. Under the United Nations Framework Convention on Climate Change (UNFCCC) and the Kyoto Protocol, greenhouse gas (GHG) emissions from peatlands managed for extraction are reported on an annual basis. However, the Tier 1 (default) emission factors (EFs) provided in the IPCC 2013 Wetlands Supplement for this land use category may not be representative in all cases and countries are encouraged to move to higher Tier reporting levels with reduced uncertainty levels based on country or regional specific data. In this study, we quantified (1) CCO2-C emissions from 9 peat extraction sites in the Republic of Ireland and the United Kingdom, which were initially disaggregated by land use type (industrial vs. domestic peat extraction), and (2) a range of GHGs that are released to the atmosphere with the burning of peat. CCO2-C emissions were strongly controlled by soil temperature at the industrial sites (bare peat), and by soil temperature and leaf area index at the vegetated domestic sites. Our derived EFs of 1.70 (±0.47) and 1.64 (±0.44) t CCO2-C ha-1 yr-1 for the industrial and domestic sites respectively, are considerably lower than the Tier 1 EF (2.8 ± 1.7 t CCO2-C ha-1 yr-1) provided in the Wetlands Supplement. We propose that the difference between our derived values and the Wetlands Supplement value is due to differences in peat quality and, consequently, decomposition rates. Emissions from burning of the peat (g kg-1 dry fuel burned) were estimated to be approximately 1346 (CCO2), 8.35 (methane, CH4), 218 (carbon monoxide, CO), 1.53 (ethane, C2H6), 1.74 (ethylene, C2H4), 0.60 (methanol, CH3OH), 2.21 (hydrogen cyanide, HCN) and 0.73 (ammonia, NH3) and emphasises the importance of understanding the full suite of trace gas emissions from biomass burning, rather than focussing solely on CCO2 and CH4 emissions. Our results highlight the importance of generating reliable Tier 2 values for different regions and land-use categories. Furthermore, given that the IPCC Tier 1 EF was only based on 20 sites (all from Canada/Fenno-Scandia) we suggest that data from another 9 sites significantly expands the global dataset, as well as adding a new region. [ABSTRACT FROM AUTHOR]

One hundred N2O flux measurements were made from an area of intensively managed grazed grassland in central Scotland using a high resolution dynamic chamber method. The field contained a variety of features from which N2O fluxes were measured including a manure heap, patches of decaying grass silage, and areas of increased sheep activity. Individual fluxes varied significantly across the field varying from 2 to 79 000 μg N2O-Nm-2 h-1. Soil samples were collected at 55 locations to investigate relationships between soil properties and N2O flux. Fluxes of N2O correlated strongly with soil NO3- concentrations. Distribution of NO3- and the high spatial variability of N2O flux across the field are shown to be linked to the distribution of waste from grazing animals and the resultant reactive nitrogen compounds in the soil which are made available for microbiological processes. Features within the field such as shaded areas and manure heaps contained significantly higher available nitrogen than the rest of the field. Although these features only represented 1.1% of the area of the field, they contributed to over 55% of the total estimated daily N2O flux. [ABSTRACT FROM AUTHOR]

Ecosystems are frequently disturbed by fires that have an important impact on the soil environment and the composition of soil organisms. In order to provide a baseline for the current research and identify trends on the effects of wildland fire on soil environment and biological changes, the available literature was identified from the Web of Science database, covering the period from 1998/1998/1999 (the year of the earliest publication in this field) to 2023. A bibliometric analysis was performed and the data were visually displayed for the number of publications, countries, authors, research institutions, and keywords representing research hotspots. Specifically, the effects of wildland fire on the soil environment, on soil microorganisms and on soil fauna were analyzed. The results show that the annual number of publications describing effects of wildland fire on the soil environment and on soil microorganisms are increasing over time, while those describing effects on soil fauna are fewer and their number remains constant. The largest number of papers originate from the United States, with the United States Department of Agriculture as the research institution with the largest output. The three authors with the largest number of publications are Stefan H. Doerr, Manuel Esteban Lucas-Borja and Jan Jacob Keizer. The research hotspots, as identified by keywords, are highly concentrated on wildfire, fire, organic matter, and biodiversity, amongst others. This study comprehensively analyzes the current situation of the research on the effects of wildland fire on changes in the soil environment and organisms, and provides reference for relevant scientific researchers in this trend and future research hotspots. [ABSTRACT FROM AUTHOR]

Peatlands cover only 3–4% of the Earth's surface, but they store nearly 30% of global soil carbon stock. This significant carbon store is under threat as peatlands continue to be degraded at alarming rates around the world. It has prompted countries worldwide to establish regulations to conserve and reduce emissions from this carbon rich ecosystem. For example, the EU has implemented new rules that mandate sustainable management of peatlands, critical to reaching the goal of carbon neutrality by 2050. However, a lack of information on the extent and condition of peatlands has hindered the development of national policies and restoration efforts. This paper reviews the current state of knowledge on mapping and monitoring peatlands from field sites to the globe and identifies areas where further research is needed. It presents an overview of the different methodologies used to map peatlands in nine countries, which vary in definition of peat soil and peatland, mapping coverage, and mapping detail. Whereas mapping peatlands across the world with only one approach is hardly possible, the paper highlights the need for more consistent approaches within regions having comparable peatland types and climates to inform their protection and urgent restoration. The review further summarises various approaches used for monitoring peatland conditions and functions. These include monitoring at the plot scale for degree of humification and stoichiometric ratio, and proximal sensing such as gamma radiometrics and electromagnetic induction at the field to landscape scale for mapping peat thickness and identifying hotspots for greenhouse gas (GHG) emissions. Remote sensing techniques with passive and active sensors at regional to national scale can help in monitoring subsidence rate, water table, peat moisture, landslides, and GHG emissions. Although the use of water table depth as a proxy for interannual GHG emissions from peatlands has been well established, there is no single remote sensing method or data product yet that has been verified beyond local or regional scales. Broader land-use change and fire monitoring at a global scale may further assist national GHG inventory reporting. Monitoring of peatland conditions to evaluate the success of individual restoration schemes still requires field work to assess local proxies combined with remote sensing and modeling. Long-term monitoring is necessary to draw valid conclusions on revegetation outcomes and associated GHG emissions in rewetted peatlands, as their dynamics are not fully understood at the site level. Monitoring vegetation development and hydrology of restored peatlands is needed as a proxy to assess the return of water and changes in nutrient cycling and biodiversity. [ABSTRACT FROM AUTHOR]

Copyright of Earthquake (1000-3274) is the property of Editorial Office of Earthquake Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Drained organic soils are anthropogenic emission hotspots of greenhouse gases (GHGs). Most studies have focused on deep peat soils and on peats with high organic carbon content. In contrast, Histic gleysols are characterized by shallow peat layers, which are left over from peat cutting activities, or by peat mixed with mineral soil. It is unknown whether they emit less GHGs than deep Histosols when drained. We present the annual carbon and GHG balance of grasslands for six sites on nutrient-poor histic gleysols with a shallow (30 cm) histic horizon or mixed with mineral soil in Northern Germany (soil organic carbon concentration (Corg) from 9 to 52%). The net GHG balance, corrected for carbon export by harvest, was around 4t CO2-C-eq. ha-1yr-1 on soils with peat layer and little drainage (mean annual water table < 20 cm below surface). The net GHG balance reached 7-91 CO2-C-eq. ha-1 yr-1 on soils with peat layer and deeper drainage (mean annual water table > 20 cm below surface) and on soils with sand mixed into the histic horizon, independent of water table level. GHG emissions from drained histic gleysols (i) were as high as those from deep histosols, (ii) linearly related to water table, (iii) but not affected by Corg content of the histic horizon. Ecosystem respiration (Reco) was linearly correlated with water table level even if it was below the histic horizon. The Reco : GPP ratio was 1.5 at all sites, so that we ruled out a major influence of the inter-site variability in vegetation composition on annual net ecosystem exchange (NEE). The IPCC definition of organic soils includes shallow histic topsoil, unlike most national and international definitions of histosols. Our study confirms that this broader definition is appropriate considering anthropogenic GHG emissions from drained organic soils. Countries currently apply soil maps in national GHG inventories which are likely not to include histic gleysols. The land area with GHG emission hotspots due to drainage is likely to be much higher than anticipated. Deeply drained histic gleysols are GHG hotspots which have so far been neglected or underestimated. Peat mixing with sand does not mitigate GHG emissions. Our study implies that rewetting organic soils, including histic gleysols, has a much higher relevance for GHG mitigation strategies than currently recognized. [ABSTRACT FROM AUTHOR]

The article presents a study on the detecting hotspots of atmosphere-vegetation interaction via slowing down phenomenon. The study which used Early Warning Signals (EWS) was performed to the atmosphere-vegetation model PlanetSimulator (PlaSim)-VECODE with surrogate stochastic toy model. The study shows that the model can provide information on the causality of sudden transitions of climatic models.

Biochar has excellent physical and chemical properties such as porosity, high carbon content, high cation exchange capacity, and rich surface functional groups and has been widely used in environmental remediation. Over the past 20 years, although various reviews have described the application of biochar as an environmentally friendly multifunctional material in environmental remediation, no comprehensive summary and analysis of the research trends in this field exists. To promote the rapid and stable development of the field of biochar, the current state of research on biochar is clarified using the bibliometric method in this report, and potential development directions and challenges for the future are identified. All relevant biochar literature from 2003–2023 was collected from the Chinese National Knowledge Infrastructure and Web of Science Core Collection. A total of 6,119 published Chinese papers and 25,174 English papers were selected for the quantitative analysis. CiteSpace, VOSviewer, and Scimago graphics software was used to summarize the numbers of papers published over the years, as well as the countries, institutions, and authors that published the most articles. Secondly, using keyword co-occurrence and emergence analysis, the recognized research hotspots in different areas such as adsorbents, soil remediation, catalytic oxidation, supercapacitors, and "biochar-microbial" synergy were analyzed. Finally, the prospects and challenges of biochar were assessed to provide new perspectives for further promoting its development in technological, economic, environmental, and other aspects. [ABSTRACT FROM AUTHOR]

Copyright of Ecological Science is the property of Ecological Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The phrase 'hot spots and hot moments' first entered the lexicon in 2003, following the publication of the paper 'Biogeochemical hot spots and hot moments at the interface of terrestrial and aquatic ecosystems' by McClain and others (Ecosystems 6:301-312, 2003). This paper described the potential for rare places and rare events to exert a disproportionate influence on the movement of elements at the scale of landscapes and ecosystems. Here, we examine how the cleverly named hot spot and hot moment concept (hereafter HSHM) has influenced biogeochemistry and ecosystem science over the last 13 years. We specifically examined the extent to which the HSHM concept has: (1) motivated research aimed at understanding how and why biogeochemical behavior varies across spatiotemporal scales; (2) improved our ability to detect HSHM phenomena; and (3) influenced our approaches to restoration and ecosystem management practices. We found that the HSHM concept has provided a highly fertile framework for a substantial volume of research on the spatial and temporal dynamics of nutrient cycling, and in doing so, has improved our understanding of when and where biogeochemical rates are maximized. Despite the high usage of the term, we found limited examples of rigorous statistical or modeling approaches that would allow ecosystem scientists to not only identify, but scale the aggregate impact of HSHM on ecosystem processes. We propose that the phrase 'hot spots and hot moments' includes two implicit assumptions that may actually be limiting progress in applying the concept. First, by differentiating 'hot spots' from 'hot moments,' the phrase separates the spatial and temporal components of biogeochemical behavior. Instead, we argue that the temporal dynamics of a putative hot spot are a fundamental trait that should be used in their description. Second, the adjective 'hot' implicitly suggests that a place or a time must be dichotomously classified as 'hot or not.' We suggest instead that each landscape of interest contains a wide range of biogeochemical process rates that respond to critical drivers, and the gradations of this biogeochemical topography are of greater interest than the maximum peaks. For these reasons, we recommend replacing the HSHM terminology with the more nuanced term ecosystem control points. 'Ecosystem control' suggests that the rate must be of sufficient magnitude or ubiquity to affect dynamics of the ecosystem, while 'points' allows for descriptions that simultaneously incorporate both spatial and temporal dynamics. We further suggest that there are at least four distinct types of ecosystem control points whose influence arises through distinct hydrologic and biogeochemical mechanisms. Our goal is to provide the tools with which researchers can develop testable hypotheses regarding the spatiotemporal dynamics of biogeochemistry that will stimulate advances in more accurately identifying, modeling and scaling biogeochemical heterogeneity to better understand ecosystem processes. [ABSTRACT FROM AUTHOR]

At present, 5G base stations are densely distributed in major cities based on improving user concentrations and the large demand for services in urban hotspot areas. Moreover, 5G communication requires more accurate communication propagation loss (PL) monitoring. Low-build areas, such as suburbs and rural areas, are prone to forming relatively stable tropospheric ducts, which can bend the signal to the surface in the duct-trapping layer for multiple reflections. Due to the random flow of the atmospheric air mass, each reflection of the communication signal is re-scattered in the troposphere through the top of the duct layer, thereby expanding the propagation range of the signal and changing the expected effect of radio wave propagation. If ducting and troposcatter effects happen in the 5G base station antenna layer, co-channel interference (CCI) could occur, affecting the quality of electromagnetic propagation. Urban links in the plain area have no major terrain obstacles, but ground fluctuations and land cover scattering have a greater impact on the signal scattering at the bottom of the duct. On the basis of the forward-propagation theory, this paper adds factors, such as ducting the forecast value using real weather parameters, terrain, and land cover-type distributions to evaluate the CCIs of over-the-horizon communications on the intercity link. Based on 1300 sets of randomly generated terrains and landforms, two deep learning (DL) models were used to predict the PL of over-the-horizon communications between cities in a land-based ducting environment. The accuracy of LSTM prediction could reach 98.4%. The verification of PL prediction using DL in this paper allows for quick and efficient prediction of PL in the land-based ducting of intercity links using land cover characteristics. [ABSTRACT FROM AUTHOR]

The Hulan River Basin is located in the black soil region of northeast China. This region is an important food-producing area and the susceptibility of black soil to erosion increases the risk of soil erosion, which is a serious environmental problem that affects agricultural productivity, water supply, and other important aspects of the region. In this paper, the changes in LULC (land use and land cover) in the basin between 2001 and 2020 were thoroughly analysed using GIS (geographic information system) and USLE (universal soil loss equation) models. The soil erosion risk in the Hulan River Basin between 2001 and 2020 was also studied and soil erosion hot spots were identified to target those that remained significant even under the implementation of soil conservation measures. Precipitation data were used to obtain the R factor distribution, LULC classification was adopted to assess the C factor distribution, soil data were employed to estimate the K factor distribution, DEM (Digital Elevation Model) data were used to generate an LS factor map, and slope and LULC data were considered to produce a P factor distribution map. These factors were based on the model parameters of the USLE. The findings of LULC change analysis over the last 20 years indicated that, while there have been nonobvious changes, agricultural land has continued to occupy the bulk of the area in the Hulan River Basin. The increase in areas used for human activities was the most notable trend. In 2001, the model-predicted soil erosion rate varied between 0 and 120 t/ha/yr, with an average of 4.63 t/ha/yr. By 2020, the estimated soil erosion rate varied between 0 and 193 t/ha/yr, with an average of 7.34 t/ha/yr. The Hulan River Basin was classified into five soil erosion risk categories. Most categories encompassed extremely low-risk levels and, over the past 20 years, the northeastern hilly regions of the basin have experienced the highest concentration of risk change areas. The northeastern hilly and mountainous regions comprised the risk change area and the regions that are most susceptible to erosion exhibited a high concentration of human production activities. In fact, the combined use of GIS and USLE modelling yielded erosion risk areas for mapping risk classes; these results could further assist local governments in improving soil conservation efforts. [ABSTRACT FROM AUTHOR]

Context: The study of sustainable land use reflects the interdisciplinary characteristics of land science, geography, ecology and sustainability science. In recent years, research on sustainable land use has rapidly increased in scope and speed around the world. Objectives: To discuss the trends, research power distribution, key areas, research hotspots and international cooperation in sustainable land use research in the past 20 years. Methods: This paper used the Bibliometrix and Biblioshiny software packages to entire process of bibliometric analysis and visual display of sustainable land use research papers from 1990 to 2019 (data update time is May 10, 2019). Results: (1) The amount of publications in the field of sustainable land use from 1990 to 2019 increased with time and entered a period of rapid growth after 2013. (2) From the perspective of research power, the influence of developed countries in the field of sustainable land use is significantly stronger than that of developing countries. (3) Through high-frequency keyword analysis, land use change, land degradation, and sustainable land management are hotspots in the field of sustainable land use. (4) The themes of sustainable land use have changed greatly in various periods, and some of the themes have strong continuity. Conclusions: In order to promote the development of sustainable land use, this paper proposes to integrate strong sustainability theory, landscape ecology theory, and geographical design concepts into this field, thereby greatly expanding the theoretical space. Also, this paper proposes to improve the scientificity of the evaluation indicators and use emerging technologies to timely monitor the status and evolution of land use, which can provide scientific basis and decision-making reference for the formulation of sustainable land use strategies, policies, and countermeasures. [ABSTRACT FROM AUTHOR]

Six agricultural landscapes in Poland (PL), the Netherlands (NL), France (FR), Italy (IT), Scotland (UK) and Denmark (DK) were studied, and a common method was developed for undertaking farm inventories and the derivation of farm nitrogen (N) balances and N surplus from the in total 222 farms and 11 440 ha of farmland. In all landscapes, a large variation in the farm N surplus was found, and thereby a large potential for reductions. The highest average N surpluses were found in the most livestock-intensive landscapes of IT, FR, and NL; on average 202±28, 179±63 and 178±20 kgNha-1 yr-1, respectively. However, all landscapes showed hotspots, especially from livestock farms, including a special UK case with landless large-scale poultry farming. So, whereas the average N surplus from the land-based UK farms dominated by extensive sheep grazing was only 31±10 kgNha-1 yr-1, the landscape average was similar to those of PL and DK (122±20 and 146±55 kgNha-1 yr-1, respectively) when landless poultry were included. However, the challenge remains how to account for indirect N surpluses and emissions from such farms with a large export of manure out of the landscape. We conclude that farm N balances are a useful indicator for N losses and the potential for improving N management. Significant correlations to N surplus were found, both with ammonia air concentrations and nitrate levels in soils and groundwater, measured during the landscape data collection campaign from 2007-2009. This indicates that farm N surpluses may be used as an independent dataset for validation of measured and modelled N emissions in agricultural landscapes. However, no significant correlation was found to N measured in surface waters, probably because of the short time horizon of the study. A case study of the development in N surplus from the landscape in DK from 1998-2008 showed a 22% reduction, related to statistically significant effects (p < 0.01) of measures targeted at reducing N emissions from livestock farms. Based on the large differences between the average and the most modern and N-efficient farms, it was concluded that N-surplus reductions of 25--50% as compared to the present level were realistic in all landscapes. The implemented N-surplus method was thus effective at comparing and synthesizing results on farm N emissions and the potentials of mitigation options, and is recommended for use in combination with other methods for the assessment of landscape N emissions and farm N efficiency, including more detailed 5 N sink and N source hotspot mapping, measurements and modelling. [ABSTRACT FROM AUTHOR]

Fixed nitrogen (N) loss to biogenic N2 in intense oceanic O2 minimum zones (OMZ) accounts for a large fraction of the global N sink and is an essential control on the ocean's N budget. However, major uncertainties exist regarding microbial pathways as well as net impact on the magnitude of N-loss and the ocean's overall N budget. Here we report the discovery of a N-loss hotspot in the Peru OMZ associated with a coastally trapped mesoscale eddy that is marked by an extreme N deficit matched by biogenic N2 production, high NODue to image rights restrictions, multiple line equation(s) cannot be graphically displayed. levels, and the highest isotope enrichments observed so far in OMZ's for the residual NODue to image rights restrictions, multiple line equation(s) cannot be graphically displayed. High sea surface chlorophyll (SSC) in seaward flowing streamers provides evidence for offshore eddy transport of highly productive, inshore water. Resulting pulses in the downward flux of particles likely stimulated heterotrophic dissimilatory NODue to image rights restrictions, multiple line equation(s) cannot be graphically displayed. reduction and subsequent production of biogenic N2. The associated temporal/spatial heterogeneity of N-loss, mediated by a local succession of microbial processes, may explain inconsistencies observed among prior studies. Similar transient enhancements of N-loss likely occur within all other major OMZ's exerting a major influence on global ocean N and N isotope budgets. [ABSTRACT FROM AUTHOR]

Biochar has been paid great attentions during the last two decades, because of its resources potentials and environmental benefits. A bibliometric analysis was applied to assess the publications regarding the keyword biochar from the Web of Science database during the period of 1999 to 2018. A total of 8629 publications were obtained with a rapid increase of annual citations and number of papers. The research topics were diversified, which were mainly divided into "Environmental Sciences and Ecology," "Agriculture," and "Engineering." Bioresource Technology was the journal which published most of the relevant papers. China ranked first in the number of published papers, followed by the USA, Australia, UK, and Germany. Especially, China established close collaboration with the USA in joint publication. Analysis of the keywords indicated that biochar production, comparative sorption, soil-applied black carbon, and soil management were the main research hotspots of biochar. The burst detection reflected that the innovation of biochar production and the new application field of biochar was the future research trends. These results can provide insight into the research progress regarding biochar. [ABSTRACT FROM AUTHOR]

Climate change is recognised among the drivers of conflicts in developing regions but the growing studies on climate change–violent conflict nexus in Africa have paid little attention to the spatial dimension of the farmer–herder conflict in Nigeria. Existing studies have not explored the issue of climate change vulnerability regarding the farmer–herder conflict. Therefore, this paper contributes to the literature by examining the spatial dimension of the relationship between climate change and farmer–herder conflict vulnerabilities in Nigeria. Data were obtained from various secondary sources and the analyses were based on climate security vulnerability model. The study shows that the farmer–herder conflict is widespread across Nigeria but with significant spatial clustering and the hotspot is in the Middle Belt, especially in Benue State. The result of the regression model indicates that climate change vulnerability is the best predictor of the farmer–herder conflict in Nigeria but the effect is negative. This result implies that regions more vulnerability to climate change experience lesser farmer–herder conflict. The paper demonstrates that climate change could influence herders' migration pattern as the herders now move southward due to deteriorating environmental conditions partly caused by changing climate in the northern regions. Thus, it argues climate change is not necessarily the cause of the conflict because the change in the pattern of herder's migration does not automatically lead to climate change causing conflict. Migration is important but the mechanism establishing the migration–conflict nexus has to be explained by taking cognisance of identity differentials between herding groups and local communities. [ABSTRACT FROM AUTHOR]

Water quality has emerged as a fast-developing research area. Regular assessment of research activity is necessary for the successful R&D promotion. Water quality research work carried out in different countries increased over the years, and the USA ranked first in productivity while India stands in the seventh position in quantity and occupies the ninth position in quality of the research output. India observes a steady growth in the water quality research. Four thousand six hundred sixteen articles from India assessed from the aspect of citations received distributions of source countries, institutes, journals, impact factor, words in the title, author keywords. The qualitative and quantitative analysis identifies the contributions of the major institutions involved in research. Much of the country’s water quality research is carried out by universities, public research institutions and science councils, whereas the contribution from Ministry of water resources not so significant. A considerable portion of Indian research is communicated through foreign journals, and the most active one is Environmental Monitoring and Assessment journal. Twenty-one percent of work is reported in journals published from India and around 7% ages in open access journals. The study highlights that international collaborative research resulted in high-quality papers. The authors meticulously analyse the published research works to gain a deeper understanding of focus areas through word cluster analyses on title words and keywords. When many papers deal with ‘contamination’, ‘assessment’ and ‘treatment’, enough studies done on ‘water quality index’, ‘toxicity’, considerable work is carried out in environmental, agricultural, industrial and health problems related to water quality. This detailed scientometric study from 1,09,766 research works from SCI-E during 1986-2015 plots the trends and identifies research hotspots for the benefit to scientists in the subject area. This study comprehends the magnitude of water quality research also establishes future research directions using various scientometric indicators. [ABSTRACT FROM AUTHOR]

The quality and vitality of cities largely depend on the design, management, and maintenance of green areas, including urban protected areas (UPAs), since they provide multiple benefits for the city. Due to urbanization and higher anthropogenic pressure, green areas are decreasing which directly affects natural habitats and biodiversity. This study aims to assess soil and vegetation chemical status in UPAs in the city of Belgrade, Serbia, and to understand how their distance from pollution hotspots affects soil and vegetation quality. Additionally, this paper considers the inclusion of soil and vegetation conditions in the urban protected areas management as a basis for introducing a connectivity approach to expand green infrastructure throughout the city. Chemical properties, the content of nutrients (C, N, P, and K), and microelements (Cr, Co, Ni, Cu, Zn, As, Cd, Sn, Pb, Zr, U, and Th) in soil and conifer needles were analyzed. Results showed that the distance of pollution hotspots does not affect nutrient and microelements concentrations in soil, i.e., they do not vary significantly between sites and do not exceed remediation intervention values. However, the microelements status of vegetation is affected since Cr, Cu, Zn, Sn, and Pb are higher in needles from trees from the city center. The state of soil and plant composition supports the establishment of a network of green corridors and should become a part of management strategies, thus helping biodiversity protection, climate change mitigation, and human well-being in the cities. [ABSTRACT FROM AUTHOR]

Within any scientific disciplines, a large amount of data are buried within various literature depositories and archives, making it difficult to manually extract useful information from the datum swamps. The machine-learning extraction of data therefore is necessary for the big-data-based studies. Here, we develop a new text-mining technique to reconstruct the global database of the Precambrian to Recent stromatolites, providing better understanding of secular changes of stromatolites though geological time. The step-by-step data extraction process is described as below. First, the PDF documents of stromatolite-containing literatures were collected, and converted into text formation. Second, a glossary and tag-labeling system using NLP (Natural Language Processing) software was employed to search for all possible candidate pairs from each sentence within the papers collected here. Third, each candidate pair and features were represented as a factor graph model using a series of heuristic procedures to score the weights of each pair feature. Occurrence data of stromatolites versus stratigraphical units (abbreviated as Strata), facies types, locations, and age worldwide were extracted from literatures, respectively, and their extraction accuracies are 92%/464, 87%/778, 92%/846, and 93%/405 from 3 750 scientific abstracts, respectively, and are 90%/1 734, 86%/2 869, 90%/2 055 and 91%/857 from 11 932 papers, respectively. A total of 10 072 unique datum items were identified. The newly obtained stromatolite dataset demonstrates that their stratigraphical occurrences reached a pronounced peak during the Proterozoic (2 500–541 Ma), followed by a distinct fall during the Early Phanerozoic, and overall fluctuations through the Phanerozoic (541–0 Ma). Globally, seven stromatolite hotspots were identified from the new dataset, including western United States, eastern United States, western Europe, India, South Africa, northern China, and southern China. The proportional occurrences of inland aquatic stromatolites remain rather low (∼ 20%) in comparison to marine stromatolites from the Precambrian to Jurassic, and then display a significant increase (30%–70%) from the Cretaceous to the present. [ABSTRACT FROM AUTHOR]

Soil moisture is a key factor in ecosystems that profoundly affects carbon, nitrogen, and water cycles on land surfaces, vegetation growth, and climate change. Consequently, numerous scholars have researched and authored scientific literature on soil moisture and related topics. Using the Web of Science database, we conducted a bibliometric analysis of 60,581 papers published in the field of soil moisture between 2000 and 2022. The findings revealed the following trends. (1) The number of publications on soil moisture has consistently increased in the 21st century at an increasing rate. For instance, although the annual increase was only 94 publications in 2005, it surged to 321 publications in 2020. (2) The United States (US), China, and developed European countries emerged as primary research institutions and authors. The US occupies a leading position in soil moisture research, boasting the highest number of publications and total citations in the field, whereas China ranks second in both publications and total citations. (3) Regarding international collaboration, the US has established close partnerships with numerous international research institutions. However, China's international cooperation in this field requires improvement. (4) The Journal of Hydrology holds the top position in terms of both the total number of published articles and citations. Research on water resources ranked first in terms of its H-index. (5) Keyword analysis highlighted several current research hotspots, including the coupled covariance effect of soil moisture and land surface environmental factors in the context of climate change, soil moisture utilization rate, crop yield, influence mechanism of soil moisture on soil ecosystem structure, and development of high-precision soil moisture data products. In conclusion, this study provides a systematic review of the research hotspots and trends in soil moisture studies in the 21st century. The objective is to offer a comprehensive reference to aid in understanding the evolutionary patterns of soil moisture research in multiple dimensions. [ABSTRACT FROM AUTHOR]

Resources are essential for human survival and development, and resource security occupies an important position in national security. With the increasing resource shortage problem, ecological stability is facing severe challenges. All countries are actively seeking new sustainable development ways to deal with various issues and shocks caused by the shortage of resources. This study aims to systematically and comprehensively evaluate the knowledge structure, research hotspots, and resource security evolution trends. Based on the number of 6391 articles retrieved from the Web of Science database from 1990 to 2021, this article carried out a visual analysis of global resource security research from the perspectives of scientific output characteristics, keywords, and highly cited literature scientific collaboration networks and hotspot emergence analysis. The research results show that after humans have experienced new public safety incidents, their understanding of resource security and sustainable development has risen to a new height. The number of relevant documents is increasing rapidly. At present, the research on resource security is still dominated by developed countries in Europe and America. This study finds that "food supply chain," "water availability," and "soil resources suitability" are the frontiers and hotspots in the field of resource security. Besides, "biodiversity," "mineral resource security," "medical and health resources" are important topics and directions of current research. This study provides a theoretical basis for scholars to explore the future research direction and practice of resource security, to achieve ecological stability and sustainable development. [ABSTRACT FROM AUTHOR]

The reality of global climate change demands novel approaches to science that are reflective of the scales at which changes are likely to occur, and of the new forms of knowledge required to positively influence policy to support vulnerable populations. We examine some of the opportunities and challenges presented by a collaborative, transdisciplinary research project on climate change adaptation in Africa and Asia that utilized a hotspot approach. A large-scale effort to develop appropriate baselines was a key challenge at the outset of the program, as was the need to develop innovative methodologies to enable researchers to work at appropriate spatial scales. Efforts to match research to the biophysical scales at which change occurs need to be aware of the mismatch that can develop between these regional scales and the governance scales at which decisions are made. [ABSTRACT FROM AUTHOR]

Green supply chain (GSC), one of the most vital sub-topics of sustainable development, indicates people provoking on the rationality of business practices and resource consumption patterns. Under the background of economy globalization, developing countries, especially China, severely affected by green barriers became the global focus. A systematic review of articles about GSC which published in leading journals of Web of Science Core Collection (WoSCC) and China Knowledge Resource Infrastructure (CNKI) is proposed for exploring publishing trends, the distribution of authors and journals, research topics, and hotspots and predicting frontiers by utilizing VOSviewer, Sci2, and CiteSpace. The results show that (1) there are differences in the attention of GSC between international and Chinese academia. (2) "Green" is referred to environmental friendly practices in international academia. Scholars advocate to promote management to strengthen cooperation among GSC members and boost technology investment to improve the comprehensive performance; however, specific practices such as "low-carbon," "emission reduction," "recycling," and "remanufacture" are referred to environmental friendly behaviors in Chinese academia. Scholars expect to avoid enterprises' short-term profit compression relying on government subsidies and make contracts to share environment protection cost equally out for ensuring GSC stable operation. (3) Exploring collaboration among GSC members using complex operation research and artificial intelligence will be international research frontier. Relevant papers are to provide Chinese research with merely innovation in methodology. Besides, the "government-enterprise-university-research institute-customer-economy" management mode proposed by development countries like China will enrich the international GSC research scope, leading international GSC knowledge structure to change. The contribution of this study is to afford reference for future research on GSC. [ABSTRACT FROM AUTHOR]

Satellite observations show that there is a wintertime hotspot of gravity wave activity, located mainly over the ocean, around 60°S in the stratosphere. However, the sources of the gravity waves making up this hotspot are varied and complex and remain unclear. Here we use radiosonde observations from 11 Antarctic stations and selected small islands close to 60°S to examine the horizontal directional pseudo‐momentum flux and energy density distributions of upward propagating gravity waves in the lower stratosphere. This paper shows, for the first time, that short vertical wavelength gravity waves in the lower stratosphere clearly propagate meridionally toward 60°S during the winter months. This result supports previous studies that show that this belt of gravity wave activity over the ocean is contributed to by wave sources outside 60°S. Plain Language Summary: Atmospheric gravity waves are buoyancy waves, where the restoring force is gravity, which can have horizontal wavelengths from a few tens to hundreds of kilometers. They can be generated by a variety of sources including wind flow over mountains and storms. Over the Drake Passage and out to the east around 60°S, a large hotspot of gravity waves has been observed in the wintertime stratosphere using satellite observations. The sources for this gravity wave hotspot are unclear as it mainly located over the open ocean. In this paper radiosonde observations are used to examine, for the first time, the directional variation in short vertical wavelength gravity waves close to 60°S in the lower stratosphere. It is found that during the winter months there is a meridional convergence of gravity waves toward 60°S, implying that the gravity wave sources of the hotspot are in fact be outside this region. Key Points: This paper provides evidence of a winter time convergence of gravity waves and their momentum flux toward 60°SThis is the first time this has been observed for short vertical wavelength waves in the lower stratosphere [ABSTRACT FROM AUTHOR]

Declining groundwater levels due to the absence of a planning system makes aquifers vulnerable to subsidence. This paper investigates possible hotspots in terms of Subsidence Vulnerability Indices (SVI) by applying the ALPRIFT framework, introduced recently by the authors by mirroring the procedure for the DRASTIC framework. ALPRIFT is suitable to cases, where data is sparse, and is the acronym of seven data layers to be presented in due course. It is a scoring technique, in which each data layer bears an aspect of land subsidence and is prescribed with rates to account for local variability, and with prescribed weights to account for relative significance of the data layer. The inherent subjectivity in prescribed weights is treated in this paper by learning their values from site-specific data by the strategy of using artificial intelligence to learn from multiple models (AIMM). The strategy has two levels: (i) at Level 1, three fuzzy models are used to learn weight values from the local data and from observed target data, and (ii) at Level 2, genetic expression algorithm (GEP) is used to learn further, in which the outputs of the models at Level 1 are reused as its inputs and observed data as its target values. The results show that (i) the Nash-Sutcliff Efficiency (NSE) coefficient for ALPRIFT with measured land subsidence values is approx. 0.21; (ii) NSE is improved to 0.88 by learning the weights at Level 1 using fuzzy logic, and (iii) NSE is further improved to 0.94 by further learning at Level 2 using GEP. [ABSTRACT FROM AUTHOR]

Estuaries are biogeochemical hot spots because they receive large inputs of nutrients and organic carbon from land and oceans to support high rates of metabolism and primary production. We synthesize published rates of annual phytoplankton primary production (APPP) in marine ecosystems influenced by connectivity to land -- estuaries, bays, lagoons, fjords and inland seas. Review of the scientific literature produced a compilation of 1148 values of APPP derived from monthly incubation assays to measure carbon assimilation or oxygen production. The median value of median APPP measurements in 131 ecosystems is 185 and the mean is 252 gCm-2 yr-1, but the range is large: from -105 (net pelagic production in the Scheldt Estuary) to 1890 gCm-2 yr-1 (net phytoplankton production in Tamagawa Estuary). APPP varies up to 10-fold within ecosystems and 5-fold from year-to-year (but we only found 8 APPP series longer than a decade so our knowledge of decadal-scale variability is limited). We use studies of individual places to build a conceptual model that integrates the mechanisms generating this large variability: nutrient supply, light limitation by turbidity, grazing by consumers, and physical processes (river inflow, ocean exchange, and inputs of heat, light and wind energy). We consider method as another source of variability because the compilation includes values derived from widely differing protocols. A simulation model shows that different methods can yield up to 3-fold variability depending on incubation protocols and methods for integrating measured rates over time and depth. Although attempts have been made to upscale measures of estuarine-coastal APPP, the empirical record is inadequate for yielding reliable global estimates. The record is deficient in three ways. First, it is highly biased by the large number of measurements made in northern Europe (particularly the Baltic region) and North America. Of the 1148 reported values of APPP, 958 come from sites between 30° N and 60° N; we found only 36 for sites south of 20° N. Second, of the 131 ecosystems where APPP has been reported, 37% are based on measurements at only one location during one year. The accuracy of these values is unknown but probably low, given the large inter-annual and spatial variability within ecosystems. Finally, global assessments are confounded by measurements that are not intercomparable because they were made with a broad range of methods. Phytoplankton primary production along the continental margins is tightly linked to variability of water quality, biogeochemical processes including ocean-atmosphere CO2 exchange, and production at higher trophic levels including species we harvest as food. The empirical record has deficiencies that preclude reliable global assessment of this key Earth-system process. We face two grand challenges to resolve these deficiencies: (1) organize and fund an international effort to use a common method and measure APPP regularly across a network of coastal sites that are globally representative and sustained over time, and (2) integrate data into a unifying model to explain the wide range of variability across ecosystems and to project responses of APPP to regional manifestations of global change as it continues to unfold. [ABSTRACT FROM AUTHOR]

With the development of transportation in the west of China, tunnel construction in mountain cities is becoming very important and widespread. Tunneling safety in the tunnels is usually controlled by faults, and the advanced prediction of faults by seismic detection method has become a research hotspot in the field of engineering geophysics. Unlike seismic exploration on the ground, the sources and receivers are not properly arranged due to the limitation of the tunnel detection space, so as to cause migration artifacts problem in the process of advanced migration imaging. The problem results in inaccurate imaging of the faults. To solve the problem, this paper proposed a new polarization migration method. The method makes use of the polarization characteristic of three-component seismic signals. The principal polarization direction is calculated by Hilbert transform and complex covariance matrix analysis. A weighted function of the principal polarization direction factor is incorporated into the migration calculation. To verify the effectiveness of the polarization migration method, this paper carries out numerical simulations. Test results demonstrate that the artifacts are eliminated by the polarization migration, and occurrence parameters of faults, such as dip and trend are calculated accurately. The field detection case shows that seismic advanced prediction which is based on polarization migration provided parameters of faults in the front of the tunnel face with 100m, and the distance error is less than 2m, and the dip error is less than 3°, which ensures efficient and safe construction of tunneling. [ABSTRACT FROM AUTHOR]

The article presents the discussion on Southern Africa presenting a complex setting for the development of a unified late Quaternary chronostratigraphy covering the last 200 000 years. Topics include playing an important regional role in ocean productivity and carbon dioxide storage and exchange contributing to global climate feedbacks; and engagement between experts from the cognate disciplines in developing inter- and multi-disciplinary projects focusing at the scale of a river catchment.

Intense hydroelectric exploitation requires information on sediment flux to prevent the potential siltation of cascade reservoirs. As the main sediment source for the Yangtze River, the lower Jinsha River Basin (LJRB) lacks data on its sediment budget, which urges a thorough investigation to provide reliable estimates. This paper proposed a modelling framework to study soil erosion, sediment delivery, and sediment yield in this critical area with an emphasis on analyzing the underlying controls. Over the past 50 years, basin average erosion rates decreased from 26.5 to 23.7 t ha-1 a-1, with erosion hotspots (>50 t ha-1 a-1) comprising only 21.1% of the basin area but contributing 69.5% of the gross erosion. Local steepness and sparse landcover conditions were found to be directly responsible for high erosions, rather than precipitation or soils. With a dimensionality reduction strategy to remove redundant factors, the optimal variables for modelling sediment delivery ratio (SDR) were identified as Specific Catchment Area, Maximum Elevation, and Drainage Area. These three variables all had a positive correlation with SDR, and the established model can explain 86% of the SDR variation. Further modelling revealed regionalised SDRs ranging from 0.07 to 0.38 for 39 subbasins, about 30% of which were no less than 0.35. Regionalised specific sediment yield (SSY) ranged from 1.3 to 16.9 t ha-1 a-1 with 38% of the high SSYs (above 8 t ha-1 a-1) concentrating in the reservoir area from Wudongde to Xiluodu that poses siltation risks. This study addressed the scarcity of sediment budget knowledge in the LJRB, and the coupled model of erosion and sediment delivery has been validated with satisfactory predictions. Therefore, the modelling framework proposed may be adopted to diverse river basins for its low parameter requirements and solid modelling performance. [ABSTRACT FROM AUTHOR]

Odisha is blessed with an abundance of natural resources, including minerals, forests, marine life, and water. Odisha is one of India's top producers of valuable minerals such as chromites, nickel ore, coal, bauxite, iron ore, and manganese. In addition to providing habitat and a means of subsistence for the state's expanding tribal population, around 30 percent of its land is covered with forests, which also serve as the catchment areas of key rivers, home to rich mineral deposits and biodiversity hotspots. This article aims to analyse the current status of several extractive industries as well as their potential for the future. A significant portion of the study is based on secondary data. Simple percentage shares and yearly average growth rate have been used to analyse data and strengthen the argument. The results from the paper demonstrate that mining production and value have grown over time. However, the average yearly growth rate has been declining. The Gross State Value Added (GSVA) of the mining sector in Odisha has hardly increased and still lags behind the manufacturing sub-sector. Furthermore, the state's exchequer has profited significantly from the mining sector's performance (in terms of output, value, and income) and from its broad use of mining activities. However, employment statistics indicate that the locals in the mining region have not seen a significant increase in wealth. [ABSTRACT FROM AUTHOR]

The Guangdong–Hong Kong–Macao Greater Bay Area urban agglomeration, one of the world's four largest bay area urban agglomerations, occupies an important position in China's national development. In this paper, the expansion hotspot model, an urbanization index, a gravitation model, and a socioeconomic location model are used to explore changes in the characteristics of the urban agglomeration in the Guangdong–Hong Kong–Macao Greater Bay Area. The research results can provide decision support for government urban agglomeration planning. The research reveals the following. (1) In the skeleton maps of the expansion hotspots in the Guangdong–Hong Kong–Macao Greater Bay Area, Jiangmen shows an irregular shape, Shenzhen shows an irregular H-shape, Dongguan and Hong Kong show a shape somewhat between a circle and a star, Zhongshan shows a gourd-shape, and Guangzhou, Foshan, Huizhou, Zhaoqing, and Zhuhai show a polygon shape. (2) In 2000, 2010, and 2018, the urbanization index for the urban agglomerations were 41.78%, 50.87%, and 54.41%, respectively. The level of economic development, household registration policy, and urban planning are important factors affecting the development of urbanization. (3) The city quality and spatial connection strength of urban agglomeration have significant spatial nonequilibrium distribution characteristics. The total city quality of Shenzhen, Hong Kong, and Guangzhou accounted for more than 41.5% of the total city quality of the city cluster at the same time, and that of the east coast of the Pearl River is much stronger than the west coast. (4) There are "faults" in the socioeconomic location of the 11 cities in the urban agglomeration, with significant polarization. The socioeconomic locations of Jiangmen, Huizhou, and Zhaoqing have been below the reasonable socioeconomic location range in the past 20 years. [ABSTRACT FROM AUTHOR]

Since Al Gore created the vision for Digital Earth in 1998, a wide range of research in this field has been published in journals. However, little attention has been paid to bibliometric analysis of the literature on Digital Earth. This study uses a bibliometric analysis methodology to study the publications related to Digital Earth in the Science Citation Index database and Social Science Citation Index database (via the Web of Science online services) during the period from 1998 to 2015. In this paper, we developed a novel keyword set for ‘Digital Earth’. Using this keyword set, 11,061 scientific articles from 23 subject categories were retrieved. Based on the searched articles, we analyzed the spatiotemporal characteristics of publication outputs, the subject categories and the major journals. Then, authors’ performance, affiliations, cooperation, and funding institutes were evaluated. Finally, keywords were examined. Through keyword clustering, research hotspots in the field of Digital Earth were detected. We assume that the results coincide well with the position of Digital Earth research in the context of big data. [ABSTRACT FROM AUTHOR]

Analysis of the development of research and technical application is a critical basis for the identification and evaluation for suitable soil and water conservation ecological technology (SWCET) in China. Among instruments for analyzing the development of research and technical application, bibliometric statistics and visualization tools such as CiteSpace have been widely applied. To analyze the domestic development of SWCET, we applied CiteSpace to the CNKI (China National Knowledge Infrastructure) database on Chinese research literature (from Jan 1985 to Mar 2017) and patents (Jan 2002 to Feb 2017). The circulation of research after 2002 and quantity of patents after 2010 increased rapidly. Research institutions, people and interests were dispersed, a strong center of research has not been formed and cooperation among research institutions is weak. The number of patented inventions in western regions of China suffering serious soil erosion is far lower than that in eastern regions such as Jiangsu, Beijing, Shandong and Guangdong. Vegetation restoration, ecological slope protection and protective cultivation are relative hotspots according to technical measures: the Loess Plateau, stony desertification (area) and dry-hot valley according to research area, and expressway, side slope and sloping cropland according to application area. Research hotspots mainly appeared several years after the number of published papers increased in 2002. In the past five years, only stony desertification has emerged as a focus. We argue that further studies on the identification and evaluation of SWCET should be focused on certain technical measures, regions and areas. [ABSTRACT FROM AUTHOR]

Conventional emission permit markets are inefficient for non-uniformly mixed pollutants that create geographic 'hot spots' of different ambient emission concentrations and environmental damage. Economically efficient ambient concentration contribution markets involve difficult interactions among multiple markets that makes them practically infeasible. Extending economic theory by Muller and Mendelsohn (Am Econ Rev 99(5):1714-1739, 2009. doi:) and others about 'getting the prices right' through bilateral trading ratios, this paper introduces theoretical simplifications and a novel type of single permit market with a hybrid price-quantity instrument that addresses the dual heterogeneity of firm-specific abatement costs and regional variation in damage. This paper shows how to 'get the market right' robustly through simplicity, liquidity, and gradualism. Analytic solutions and simulation results demonstrate the feasibility of the novel market concept. Also discussed is the potential applicability of the market design to interstate trading in the United States in the wake of the recently implemented Cross-State Air Pollution Rule. [ABSTRACT FROM AUTHOR]

Increased photovoltaic installations in densely built-up areas give rise to non-uniform irradiation causing partial shading. Non-uniform irradiation further leads to non-uniform temperature, leading to a reduction in output and the formation of deteriorating hotspots. A detailed model involving subcell level behavior is pivotal in understanding the impact of partial shading. In this paper, such a model is developed that analyzes the output of photovoltaic (PV) modules under different translucent and opaque shades while incorporating the diffused light effects. This model further includes the temperature variation of the module and also captures the bypass diode characteristics. The proposed model is experimentally validated for horizontal, vertical, slant, and patch shading patterns with varying shading intensities. This subcell model is shown to perform better than four existing methods of partial shading output prediction. It improves the output open-circuit voltage and short-circuit current prediction accuracy by more than 10% when compared with the average irradiance-based modeling approach, which is the best among the existing methods. Overall, an output prediction accuracy of more than 93% is achieved for opaque shading and more than 95% for translucent shading. As this paper provides the output of PV modules under partial shading, it finds direct application in partial shading detection, prevention of hotspots, and global maximum power point tracking, thereby enhancing their life and efficiency. [ABSTRACT FROM AUTHOR]

This paper assesses the performances of runoff (Ro) and runoff coefficient (α, the ratio of runoff to precipitation) simulations from 23 models during the historical period and then projects their future changes under the two emission scenarios (SSP1‐2.6 and SSP5‐8.5) in the Coupled Model Intercomparison Project. Compared with the UNH/GRDC Ro dataset (0.82 mm day−1), the multi‐model median (MME) Ro of 1995–2014 produces a comparable global mean magnitude (0.80 mm day−1), displays a similar spatial distribution of mean Ro, and also well captures the seasonal cycles at both global and basin scales. The global mean Ro of MME is projected to be increased by 0.01–0.02 mm day−1 (SSP1‐2.6) and 0.02–0.10 mm day−1 (SSP5‐8.5) during the twenty‐first century. Regional hotspots for strong increasing Ro appear across most areas of northern high latitudes, Africa, and southeastern Asia, with high inter‐model consistency. The global mean α is projected to be slightly decreased (−0.17 to −0.63%) except for the long‐term under the SSP5‐8.5 (0.26%). Although signs of changes in Ro vary with the river basins, periods, and scenarios, α in more than half (7 out of 12) river basins are projected to decrease. The uneven distributions of projected Ro changes over global land areas are related to the response of multiple hydroclimatic variables to the global warming. Given regions with inconstancy change signs of the projected precipitation, we speculate that changes in Ro are affected by more complicated hydroclimatic processes that warrant further investigations with physical‐based approaches. Plain Language Summary: Evidence has indicated that the terrestrial hydrology would be changed unevenly over global land areas under a warmer climate. Runoff (Ro) is one of the key components of the land water budget and it represents the natural freshwater resource on the earth. This study assesses the historical simulation performances and then projects future changes in Ro and α (the ratio of runoff to precipitation) under two emission scenarios (i.e., SSP1‐2.6 and SSP5‐8.5) based on the simulations from 23 CMIP6 models. The results show that the multi‐model median Ro during the historical period is highly consistent with the reference dataset and captures the seasonal variation in most river basins. During the twenty‐first century, the multi‐model median of global mean Ro is overall projected to increase in the future and the α would slightly decrease except for the long‐term under the SSP5‐8.5. While signs and magnitudes of projection changes depend on regions and basins, those changes are more evident under higher warming levels. The uneven distributions of projected changes of Ro over global land areas are related to the response of other land surface hydrological variables to the global warming induced by anthropogenic emissions in climate models. Key Points: The runoff (Ro) and runoff coefficient (α) in CMIP6 are assessed and their future changes are projected under two SSPs in global and basin scalesThe global mean magnitude, spatial pattern, and seasonal cycles over most river basins are well reproduced by multi‐model median RoThe global mean Ro (α) is projected to increase (decrease), but their projections vary with basins and scenarios [ABSTRACT FROM AUTHOR]

This paper presents the state and spatial distribution of surface sediment contamination of 77 lakes in Poland by Cr, Ni, Cd, Pb, Zn, and Cu. The analyzed lakes were located within a network of nature protection areas in the territory of the European Union (EU). Spatial distribution of the heavy metals (HMs), factors favoring the delivery/accumulation of HMs in surface sediments, and pollution sources were analyzed. The results indicate the contamination of lake sediments by HMs, but the potentially toxic effects of HMs are only found in single lakes. The spatial distribution of Cr indicates predominant impacts of point sources, while for Pb, Ni, and Zn, the impact of non-point sources. The analysis showed the presence of areas with very high values of particular HMs (hot spots) in the western part of Poland, while a group of 5 lakes with very low values of Ni, Pb, and Zn (cold spots) was identified in the central part of Poland. Principal component analysis showed that presence of wetlands is a factor limiting HMs inflow to lakes. Also, lower HMs concentrations were found in lake surface sediments located in catchments with a higher proportion of national parks and nature reserves. Higher HMs concentrations were found in lakes with a high proportion of Special Protection Areas designated under the EU Birds Directive. The positive matrix factorization analysis identified four sources of HMs. High values of HMs concentrations indicate their delivery from industrial, urbanized, and agricultural areas. However, these impacts overlap, which disturbs the characteristic quantitative profiles assigned to these pollution sources. [ABSTRACT FROM AUTHOR]

This paper reports on laboratory-based treatability and field quality assurance (QA) testing completed on interbedded sands and silts at an industrial site heavily impacted by a chlorobenzene (CB)-rich nonaqueous phase liquid (NAPL) to depths of approximately 30 ft (9.1 m) below the ground surface (bgs). Total CB concentrations were measured up to 4,200 and 11,000 mg/kg in untreated sandy and silty soil samples, respectively. EPA 1316M testing indicated that the effective solubility of CB was on the order of 90–210 mg/L in two of the most impacted sand samples, the highest of which (from hotspot location 4370) was selected as the principal threat waste condition. A full depth [25 ft (7.6 m)] soil core from this location was homogenized to form a soil surrogate containing approximately 1,500 mg/kg CB. Three stabilization/solidification (S/S) mix designs using Type I/II portland cement (PC) doses ranging from 5 to 10 wt% were then prepared using the soil surrogate. The unconfined compressive strength (UCS) and hydraulic conductivity (K) values after 28 days of curing were, respectively, on the order of 190–265 lb/in.2 (1.31–1.83 MPa) and 1.0 × 10−9 cm/s, easily meeting the performance criteria. All mix designs showed essentially the same EPA 1315M leaching response, with percent leaching reductions (%LRs) greater than 99% for CB and benzene (B) compared with the untreated sand. This was well above the minimum of 90% LR established for successful mix designs. During remedial construction, bucket and auger S/S-mixing techniques using 7.5 wt% PC were used to treat approximately 9,335 CY of impacted soils to depths up to 30 ft (9.1 m) bgs (12 bucket-mixed cells and 527 auger columns) in approximately 6 months. The UCS and K criteria were both satisfied. The relative vertical positioning of the EPA 1315M cumulative mass release curves for CB from the field QA samples appeared to be more strongly influenced by the total CB content than by K, because all S/S-treated samples were characterized by K < 1 × 10−6 cm/s (i.e., were diffusion-controlled). EPA 1315M testing of the field-mixed sample from hotspot location 4370 again indicated %LRs greater than 99% for both CB and B. Samples from a second location in the western portion of the ISS treatment area demonstrated similar results. [ABSTRACT FROM AUTHOR]