Largest Megacity Research Articles

Global conservation priorities of coastal habitats towards extreme sea level rise risks

Approximately 70% of the world's largest megacities (>10 million people) are within 60 km of the coast, contributing to 50% of the world's GDP. Sea level rise will intensify coastal flood threats, making cities without sufficient habitat protection even more vulnerable. However, there is currently a lack of thorough evaluation at the global scale about conservation priorities based on the current habitat cover and the high sea level rise in order to adapt coastal flood risks. Here we assessed the disparity among habitat coverage, exposed population and extreme sea level rise to identify priority areas for future coastal conservation. These priority areas are characterized by a large population residing in low-elevation coastal zones (LECZs), high extreme sea levels (ESLs), and insufficient habitat coverages. In many highly populated countries like China and India, the flooding risk has been underestimated due to insufficient adaptation based on natural processes from coastal habitats. These highly populated countries are especially concerning because they have comparatively less vegetation protection capability and are subjected to high ESLs. Globally, Asian and European nations, such as China, Japan, Bangladesh, Viet Nam, the United Kingdom, Belgium, Ireland, the Netherlands, and Germany, have the highest potential for mitigating coastal risks through natural habitat conservation and restoration. We found that the main contributors to variations in the extreme sea level rise risks are not due to exposure headcounts (6%), but due to inadequate habitat cover (42%), which can be improved through targeted conservation and restoration. Our research identified the global priorities for managing climate resilience that most urgently require ecosystem conservation and restoration in order to prepare for the risks of coastal flooding.

Nanoparticles of dust as an emerging contaminant in urban environments.

Due to very high mobility in the environment and penetration ability into living organisms, nanoparticles (NPs) of urban dust pose a potential threat to human health and urban ecosystems. Currently, data on the chemical composition of NPs of urban dust, their fate in the environment, and corresponding risks are rather limited. In the present work, NPs of deposited urban dust have been comprehensively studied for the first time; NPs isolated from 78 samples of dust collected in Moscow, the largest megacity in Europe, being taken as example. The elemental composition, potential sources as well as environmental, ecological, and health risks of NPs of urban dust are assessed. It is found that dust NPs are extremely enriched by Cu, Hg, Zn, Mo, Sb, and Pb, and can serve as their carrier in urban environments. No regularities in the spatial distribution of elements have been found, probably, due to high mobility of dust NPs. High ecological and health risks caused by dust NPs are demonstrated. Source apportionment study has evaluated one natural and two anthropogenic sources of elements in NPs of urban dust; the contribution of natural and anthropogenic sources being comparable. It is also shown that dust NPs may be considered as an important carrier of trace elements in urban aquatic systems. Additionally, the risks associated with NPs and bulk samples of dust have been compared. The observed risks associated with NPs are significantly higher.

Setting S&T perspective priorities in an era of complexity and uncertainty: a case for megacities

PurposeThe purpose of this study is to create a methodological approach for identifying priority areas for science and technology (S&T) development and its empirical application within the city of Moscow. This research uncovers a wide range of multicultural and multidisciplinary global trends that will affect the development of major cities in an era of complexity and uncertainty, including the inherent complexity of urban contexts, demographic and socioeconomic trends, as well as scientific and ecological factors.Design/methodology/approachThe methodological approach is based on classic foresight instruments. Its novelty lays in the blending of qualitative and quantitative methods specially selected as the most appropriate for the identification of S&T areas in an era of complexity and uncertainty, including horizon scanning, bibliometric analysis, expert surveys and the construction of composite indexes with respect to the scope and resources of the research and the selected object for empirical application – Moscow, which is one of the world’s largest megacities. The analysis was performed for the period of 2009–2018 and expert procedures took place in 2019.FindingsAs a result, 25 global trends were identified, evaluated and discussed over the course of an expert survey and subsequent expert events. Ten priority areas of S&T development were determined, including 62 technological sub-areas within them and the most important market niches for all identified technological sub-areas, which could be useful for the world’s megacities. The results of this study are illustrated using the construction sector. Based on the conducted research and results, a list of recommendations on S&T policy measures and instruments were suggested, including the creation of the Moscow Innovation Cluster, which by the end of 2023 contained more than 6,000 projects and initiatives, selected using the findings of this investigation.Originality/valueThis research contributes to the existing literature and research agenda of setting priorities for S&T development and shows how it can be done for a megacity. The blended foresight methodology that was created within the study satisfies the criteria of scientific originality, is repeatable for any interested researcher, is applicable to any other city in the world and demonstrates its high efficiency in empirical application. It could be used for creating new agenda items in S&T policy, setting S&T priorities for a megacity and integrating the results into decision-making processes. This study provides recommendations on the further implementation of the designed methodology and results into a policymaking system. Moreover, the example of the Moscow Innovation Cluster, which was created based on the results of our research, demonstrates these recommendations’ practical significance in real life, which is quite valuable. The limitation of this study is that it is not devoted to urban planning issues directly or the promotion of R&D areas; it is about setting promising S&T priorities in an era of complexity and uncertainty for megacities.

Aerosol characterization and peculiarities of source apportionment in Moscow, the largest and northernmost European megacity

High population and a wide range of activities in a megacity lead to large-scale ecological consequences which require the assessment with respect to distinct characteristics of climate, location, fuel consumption, and emission sources. In-depth study of aerosol characteristics was carried out in Moscow, the largest megacity in Europe, during the cold period (autumn and winter) and in spring. PM10 chemical speciation based on carbonaceous matter, water-soluble ions, and elements was carried out to reconstruct the PM mass and evaluate the primary and secondary aerosol contribution. For the whole study period organic matter, mineral dust, and secondary inorganic/organic accounted for 34, 24, and 16 % of PM10 mass, respectively. PM10, OC, and EC approached a maximum in spring and decreased in winter. Mineral dust seasonal fraction increased from spring (17 %) to autumn (32 %), and then decreased in winter (22 %). Secondary inorganic aerosols (SIA) in opposite showed the maximum 27 % in winter. K+ marked the residential biomass burning in the region surrounding a megacity in spring and autumn, agriculture fires in spring. In winter primary aerosol contribution dropped down 56 % while secondary approached practically equal 44 %. Source factors with the relative contributions are quantified, namely city dust (26 %), traffic (23 %), industrial (20 %), biomass burning (12 %), secondary (12 %), and de-icing salt (7 %); they were significantly varying between the cold heating period and springtime. The relevance of sources to meteorological parameters and mass transportation is investigated by using both bivariate polar plots and Lagrangian integrated trajectory (HYSPLIT) model. Trajectory clustering demonstrates regional sources being crucial contributors to PM10 pollution. Aerosol speciation and source apportion factors identify the differences of the Moscow urban background among large European and Asian cities due to northern climate conditions, fast construction, long-range transport from industrial-developing area surrounding a city, regional biomass burning preferably in spring and autumn, and winter road management.

Fusarium Mycotoxins and OTA in Beer from Shanghai, the Largest Megacity in China: Occurrence and Dietary Risk Assessment.

Beer is susceptible to mycotoxin contamination originating from infected grains. It could be that mycotoxins are not completely removed during the brewing process and remain in the final product. Nevertheless, there have been no surveys of exposure to mycotoxin for Chinese inhabitants through beer consumption. This study aimed to investigate the presence of eight mycotoxins in 158 beer samples purchased in Shanghai, the largest megacity in China. The multiple mycotoxins determination was carried out using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Our findings revealed that 48.1% (76/158) of the beer samples were contaminated with Fusarium toxins. Deoxynivalenol-3-glucoside (D3G) and zearalenone (ZEN) were detected in 34.81% and 16.46% of the total samples, respectively. The significant differences between D3G/ZEN contamination and various beer types were performed. Furthermore, this study performed a health risk assessment for Shanghai residents based on data for Fusarium toxins and ochratoxin A (OTA) present in beer for the first time. The results revealed that the 95th percentile dietary exposures of Shanghai residents did not pose any chronic or acute health risks, either individually or in combination. Dietary exposures to Fusarium toxins revealed different risk levels among residents. The cumulative health risk for women is higher than that for men at the same beer consumption. In addition, the acute risk of DONs exposure for adults deserves concern. The insights obtained from this study may be of assistance for beer manufacturers and governmental regulators to further develop beer monitoring and guarantee public health.

Measuring Social Sustainability for Socially Sustainable Urban Development: A Preliminary Study in Dhaka City, Bangladesh

Social sustainability in socially sustainable urban development is an escalating global concern to ensure the well-being of urban society. Uncontrolled and rapid urbanization has transformed Dhaka into one of the world's largest megacities, leading to severe social problems. Therefore, it influences the city's social sustainability. Due to the lack of attention to social sustainability, especially in cities of developing countries, this study aims to measure the current status of social sustainability in Dhaka city for socially sustainable urban development. A structured questionnaire survey was conducted among residents of Dhaka. Results revealed that Dhaka city residents have low satisfaction levels regarding social sustainability conditions. They are not getting adequate facilities related to social sustainability for socially sustainable urban development. The results provide empirical evidence of the current status of social sustainability to policymakers, urban planners, and implementing agencies in Dhaka city that can assist in formulating appropriate socially sustainable planning, policy formulation, and practical implementation. The study might also help researchers in developing countries expand their thinking about other cities encountering similar problems.

Temporal Variability of Particulate Matter and Black Carbon Concentrations over Greater Cairo and Its Atmospheric Drivers

This study examines the seasonal and annual variability of black carbon (BC) and particular matter (PM1, 2.5, and 10) over Greater Cairo (Egypt) from 2003 to 2020. Data on PM and BC concentrations were gathered from the European Center for Medium-Range Weather Forecasts (ECWMF) reanalysis dataset. The Observed data from Abbasiya Station were employed to verify the accuracy of the reanalysis data, and a good agreement on both seasonal and annual scales was suggested. The results demonstrate that the highest concentrations of PM and BC were generally witnessed during wintertime, while the lowest was observed in summer. Trend analysis showed that, apart from fall, a significant increase (p < 0.05) in PM levels was evident in all seasons from 2003 to 2020. Contrarily, BC concentrations exhibited a statistically significant decline from 2003 to 2020. Moreover, BC concentrations correlated negatively with PM (1, 2.5 and 10) in all seasons and annually. However, weak and statistically non-significant (p > 0.05) correlations were found between PM and BC concentrations during wintertime. Additionally, this study looked at the atmospheric configurations corresponding to the most anomalous positive and negative phases of air pollution concentrations over Greater Cairo. The results indicate that the increase in PM concentrations is related to the positive anomalies observed at 250 hPa, which suggest a prevalence of stable atmospheric conditions, particularly during winter. Overall, our findings can serve as a foundation for improved urban planning and more effective strategies to lessen the negative effects of air quality in the largest megacity in Africa and the Middle East.

Chemical composition, sources and evolution of wintertime inorganic and organic aerosols in urban Shanghai, China

China experienced severe haze pollution in the past decades. However, systematic characterization of atmospheric fine particles with advanced measurement techniques has been very scarce in Shanghai, which is the largest megacity in China. Herein, we present the characterization of non-refractory submicron aerosol (NR-PM1) in urban Shanghai during winter 2017 by applying an Aerosol Chemical Speciation Monitor (ACSM, Aerodyne Research Inc.). The NR-PM1 is predominated by organics (43%), followed by nitrate (29%), sulfate (18%), ammonium (7%), and chloride (3%). Regarding the organic aerosol (OA) factors, three organic aerosol factors were identified and classified as hydrocarbon-like organic aerosol (HOA), less-oxygenated organic aerosol (LO-OOA), and more-oxygenated organic aerosol (MO-OOA), which contributed 32%, 22%, and 46% to total organic aerosol respectively. The NR-PM1 composition exhibited an increase in secondary inorganic aerosol (SIA) (sulfate, nitrate and ammonium) contribution from clean episodes (49%) to pollution episodes (59%), while organic aerosol contribution decreased accordingly from 48% to 39%. The strong increase of sulfate in high-relative humidity (RH) pollution episodes indicated that aqueous-phase oxidation of SO2 could be an important formation process for sulfate during particulate air pollution period. The contribution of nitrate was elevated from 25% during clean episodes to 32% during polluted episodes, likely owing to the increase of relative humidity which facilitates the hydrolysis of N2O5 and the gas-to-particle partitioning of hydrophilic NH4NO3 and. Further analysis of atmospheric formation relevance suggested that less-oxygenated organic aerosol formation was mainly driven by aqueous-phase chemistry reactions, whereas photochemical oxidation became an important process for more-oxygenated organic aerosol formation. Meanwhile, less-oxygenated organic aerosol formation may also be influenced by atmospheric oxidative tracer (i.e., Ox), as less-oxygenated organic aerosol exhibited a distinct peak at noon under high-relative humidity condition.

Mapping and simulating the spatial-temporal changes in the Lagos wetland ecosystem: A step-by-step approach to creating a carbon-neutral, sustainable urban city

BackgroundLagos is the largest megacity in Africa, with numerous lagoons and wetlands. Due to anthropogenic activities, Lagos’ wetlands have undergone significant alterations in the last few decades. The UN's Sustainable Development Goals (SDGs) and the campaign programs for carbon neutrality in the city offer a plan of action that recognizes the necessity of managing water-related habitats, such as wetlands. Wetlands are essential to accomplishing the SDGs because they provide a solution to many global issues like climate change, food insecurity, and water scarcity. In some ways, each of the SDGs is related to wetlands, but SDGs 6 and 13 are particularly significant to this study. The application of remote sensing and Geographic Information Systems (GIS) is a crucial tactic for monitoring the achievement of these SDGs. ObjectivesThe study aims to map and simulate the spatial-temporal changes in the Lagos wetland from 2000 to 2050 for the achievement of a carbon-neutral city. MethodsIn this study, Landsat ETM+ (2000, 2010) and OLI 2020 were used to monitor the spatial-temporal changes in Lagos wetlands. The maximum likelihood classification method was adopted for the supervised classification. The simulation analysis was done with the cellular automata-Markov model. ResultsThe findings show that the water body increased throughout the study, rising from 658.76 km2 in 2000 to 681.60 km2 in 2010, and to 712.0 km2 in 2020. Marshy areas have decreased progressively from 39.41 km2 in 2000 to 14.48 km2 in 2010 and 0.078 km2 in 2020. Swamps and mangrove wetland classes had changed from 448.24 km2 and 406.29 km2 in 2000 to 317.74 km2 and 538.87 km2 respectively in 2010, and to 435.29 km2 and 405.33 km2 respectively in 2020. The simulated results show that water bodies, swamps, marshy areas, and mangroves will respectively change to 711.99 km2 and 747.11 km2, 405.26 km2 and 400.16 km2, 0.15 km2 and 0.13 km2, as well as 455.29 km2 and 455.30 km2 in the simulated years 2030–2050. ConclusionThe study shows that Lagos has witnessed spatial-temporal changes in its wetland classes within the last two decades. The results prove that remote sensing and GIS are effective tools for studying water-related habitats such as wetlands.

Framework for Environmental Protection in Nigeria

This article aims to examine the development of Nigeria's environmental legislation framework. Nigeria needs help balancing economic growth and natural resource preservation as a developing country. This duality is mirrored by severe ecological problems, such as the destruction of the marine environment in the Niger Delta by crude oil and groundwater contamination in Lagos, the country's largest megacity. This research method is in-depth on normative legal research methods/library research. This article argues that more progress has yet to be made despite the greater understanding of the need to protect natural resources. The massive and ongoing contamination of vital natural resources underscores this modest increase. Investigations revealed that the same administration that set up this facility was also one of the primary violators of environmental norms and regulations. This often results in a system failure atmosphere where nothing works, and the environment suffers. The possibility of employment, environmental protection and environmental sustainability are advantages of enforcing environmental standards. Among the barriers to effective compliance with environmental regulations are outdated laws; high cost of environmental standards; weak institutional capacity; bad government; staff shortage; inadequate funding; personal interests; overlapping or conflicting laws; ignorance; and lack of the rule of law.

Ethno-confessional and socio-political views of indigenous and non-indigenous Muscovites (sociological experience)

The article deals with the problems associated with the intensification of migration processes in the largest megacities. Both positive and negative consequences of uncontrolled large-scale migration flows are determined. The focus of this article is concentrated on the study of the nature and degree of manifestation of tolerance/intolerance in the ethno-confessional and socio-cultural interaction of various groups of indigenous and non-indigenous population (with varying degrees of involvement in assimilation processes) Moscow; based on a comparative analysis of religious, socio-cultural and socio-political views of the indigenous residents of the capital and migrants. The results of monitoring by ISPR FCTAS RAS and IDR FCTAS RAS prove that uncontrolled migration processes contribute to the development of social risks. Ethno-confessional interaction is marked by the attitudes of the capital's indigenous inhabitants towards ethnocentrism, national and confessional exclusivity ("adherence to mono-national and mono-confessional marriages"). A significant difference in the socio-political, patriotic and confessional orientations of the typological groups studied ("indigenous" Muscovites and "newcomers") was revealed. Thus, the results of a sociological survey show that native Muscovites are more optimistic about the socio-economic and socio-political situation in the country, the political reform of society compared to migrants. In addition, when comparing assessments of the role of religious organizations and, in particular, the ROC in modern society, a group of "newcomers" Muscovites is less tolerant than a group of "indigenous" residents of the capital. The revealed consequences of the negative phenomena of the uncontrolled migration process (for example, the illegal involvement of migrants in labor relations contributes to the growth of the shadow economy and corruption in the labor market, etc.) indicates the relevance of studying the integration, assimilation of migrants and tolerance/intolerance in the ethno-confessional and socio-cultural interaction of indigenous Muscovites and newcomers. It is noted that taking into account "social risks" in the practice of national policy can help minimize the potential of interethnic and interfaith tensions in the metropolitan metropolis.

Urban expansion of the 43 worlds’ largest megacities: A search for unified macro-patterns

In this article, we make the case for the existence of global macro-patterns of urban change and urban growth, in particular, which may be recognized across metropolitan systems located around the globe. In order to achieve these goals, we examine the pace and types of built-up land expansion inside metropolitan regions of the 43 major megacities in the globe between 1985 and 2015. We show that the advancement of the urbanization-metropolisation process involves the sequential co-occurrence of three urban growth modes (outlying, edge expansion, and infilling). It refutes earlier claims that the three expansion modes occur simultaneously (concurrent co-occurrence) and supports the diffusion-coalescence hypothesis of urbanization. Additionally, we suggest a straightforward model based on the urban scaling laws that can be used to predict the growth of new built-up land in metropolitan areas based on the current urban mass (agglomeration effect), the availability of undeveloped land (hinterland effect), and fundamental structural elements of wider settlement systems (national-level urbanization rate and fertility). We find that the agglomeration effect is crucial for urban infilling while the hinterland effect has a greater impact on edge expansion and outlying growth. We also predict that built-up land inside the administrative regions of the studied megacities will expand by 15% (11,000 sq. km.) between 2015 and 2030. Our research thereby advances knowledge of the physical development of urban systems.

Anthropogenic factors affecting the Moskva River water quality: levels and sources of nutrients and potentially toxic elements in Moscow metropolitan area.

This study aims to identify the main patterns of distribution and sources of pollutants in the Moskva River and their influence on river water quality under different levels of anthropogenic stress caused by the largest megacity in Europe-Moscow. For this study, we determined concentrations of 18 trace elements, nutrient elements and major ions, chemical and biochemical oxygen demand, and physical parameters of water at 45 stations on the Moskva River and 20 stations on its tributaries during spring flood and low water of 2019 and 2020 to identify the extent and mechanisms of urban impact on its water chemistry. Chemical elements concentrations have been determined using ICP-MS and ICP-AES methods. Mn, Al, Cu, Sr, Zn, B, Mo, and inorganic nitrogen were outlined as key pollutants according to various drinking water and environmental guidelines. Using correlation and factor analysis, five groups of elements were identified, corresponding to different drivers controlling their unequal distribution within the watershed: mineral sources (Sr, Li, B, Mo, Ca), sewage and road runoff (TN, TP, Sb, Ni, N-NO2, BOD5, COD, V, Zn), impact of acidic wetlands (Al, COD, Zr, Bi), groundwater and landfills leachate (V, As, Pb, U, Sb), and industrial activities (Zn, Cu). Water quality in the Moskva Basin on the whole is good according to the CCME Water Quality Index. Local deterioration of water quality to marginal and even fair (depending on the reference water quality guideline) is confined to the Moskva River part downstream from the Kuryanovo aeration station to the Moskva mouth and to the mouths of several heavily contaminated tributaries.

Chemical air pollution in dwelling as a health risk factor

Up-to-date techniques applied in physical-chemical studies made it possible to identify and quantify chemical pollutants in the air inside contemporary dwelling in a large megacity and then create a database on them. This database has a list of more than 600 chemicals from 18 groups of volatile hydrocarbons and covers hygienic standards for their contents, their hazard category, and ranges of detected concentrations. Major sources of air pollution with these chemicals in dwelling were also identified. From the hygienic point of view, a significant fact is that there are no hygienic standards for more than 60 % of chemicals detected in air in dwelling. Formaldehyde, phenol, and styrene are priority chemicals for quality monitoring and risk-based control of hazards posed by chemical air pollution both in newly built houses that are at the approval stage and already exploited ones. Formaldehyde, benzene, phenol, styrene, acetophenone, ethylbenzene, hexanal, nonanal, butyl acetate, ethyl acetate, isopropanol, and trimethylbenzene are the most hygienically significant volatile organic compounds for quality control and health risk assessment considering frequency of their occurrence, concentration levels, concentrations exceeding MPC, group affiliation, hazard category, and ability to transform. When controlling natural chemicals that occur in air in dwelling due to some internal pollution sources, we should bear in mind that transformation may result in a new structure of pollution and new occurring chemicals can be more toxic and hazardous than original ones. To minimize risks associated with exposure to chemical pollution and to assess chemical safety of air in dwelling, we recommend wider use of up-to-date physical and chemical methods for qualitative and quantitative analysis thereby securing identification of a wide range of pollutants including potentially hazardous ones. Since certain chemicals have been detected for which no safety criteria have been developed so far, it is especially vital to perform research in the sphere of hygienic standardization and to develop methodical documents aimed at providing adequate hygienic assessment of quality and chemical safety of internal environment in dwelling.

Химическое загрязнение воздушной среды жилых помещений как фактор риска здоровью населения

Up-to-date techniques applied in physical-chemical studies made it possible to identify and quantify chemical pollutants in the air inside contemporary dwelling in a large megacity and then create a database on them. This database has a list of more than 600 chemicals from 18 groups of volatile hydrocarbons and covers hygienic standards for their contents, their hazard category, and ranges of detected concentrations. Major sources of air pollution with these chemicals in dwelling were also identified. From the hygienic point of view, a significant fact is that there are no hygienic standards for more than 60 % of chemicals detected in air in dwelling. Formaldehyde, phenol, and styrene are priority chemicals for quality monitoring and risk-based control of hazards posed by chemical air pollution both in newly built houses that are at the approval stage and already exploited ones. Formaldehyde, benzene, phenol, styrene, acetophenone, ethylbenzene, hexanal, nonanal, butyl acetate, ethyl acetate, isopropanol, and trimethylbenzene are the most hygienically significant volatile organic compounds for quality control and health risk assessment considering frequency of their occurrence, concentration levels, concentrations exceeding MPC, group affiliation, hazard category, and ability to transform. When controlling natural chemicals that occur in air in dwelling due to some internal pollution sources, we should bear in mind that transformation may result in a new structure of pollution and new occurring chemicals can be more toxic and hazardous than original ones. To minimize risks associated with exposure to chemical pollution and to assess chemical safety of air in dwelling, we recommend wider use of up-to-date physical and chemical methods for qualitative and quantitative analysis thereby securing identification of a wide range of pollutants including potentially hazardous ones. Since certain chemicals have been detected for which no safety criteria have been developed so far, it is especially vital to perform research in the sphere of hygienic standardization and to develop methodical documents aimed at providing adequate hygienic assessment of quality and chemical safety of internal environment in dwelling.

In pursuit of sustainability – Spatio-temporal pathways of urban growth patterns in the world's largest megacities

Governing the future growth of the world's megacities towards higher land use efficiency is important for achieving global sustainability. We have computed statistics of the urban growth modes of 33 megacities (with ten-million-plus population) worldwide for two periods (1985–2000 and 2000–2015) and performed a hierarchical cluster analysis to examine their urban growth patterns. Results reveal that urban growth has mostly occurred through edge expansion but also that its relative dominance has decreased due to the rising shares of the infilling and outlying growth modes. Based on the co-occurrence and changing dominance of these three urban growth modes over time, four pathways of urban growth patterns are identified– oscillating/ping pong, transition-to-densification, transition-to-sprawl, and extensive sprawl. The majority of megacities followed the oscillating/ping pong pathway, which is dominated by edge expansion and altered phases of infilling and outlying growth. However, by indicating a clear shift from edge expansion towards infilling as the dominant pathway of urban growth, the transition-to-densification pathway appears to be the most sustainable in terms of land-use efficiency, with ten megacities following this pathway. Overall, our results highlight the diverse mega-urban growth pathways across the world, particularly for megacities in the Global South which generally have higher growth rates.

Participation of Rossiulus kessleri (Diplopoda, Julida) in the Formation of Algae Assemblages of Urbanized Territories

Epi- and endozoochory are well explored phenomena that contribute to the distribution patterns of plant seeds, spores or fruits by vertebrates. It is less known how soil algae may be redistributed due to analogous interactions. We describe the participation of saprophage Rossiulus kessleri (Julidae, Diplopoda) in soil algae redistribution. The research was carried out in a park area of a large industrial megacity in the Dnipro steppe region (Ukrainian North Steppe subzone), Dnipro city. Research material was collected according to zoological and algological methods. The leaf litter of tree species (ash maple Acer negundo, Italian poplar Populus deltoides, locust Robinia pseudoacacia, European white elm Ulmus laevis, Norway maple Acer platanoides) and living diplopods were collected within 1 m2 quadrats along transects. Millipedes were maintained without feeding for five days, after which they were fed with the litter collected previously. Identification of algoflora was conducted in washes from the surface of diplopods’ bodies, its gut washes, in diplopods’ excretions and leaf litter washes. In the leaf litter, as R. kessleri’s feeding base, 14 soil algae species were identified—Nostoc punctiforme, Bracteacoccus minor, Mychonastes homosphaera, Neospongiococcum sp., Chlamydomonas sp., Chlorella vulgaris, Stichococcus bacillaris, Pseudococcomyxa simplex, Desmococcus olivaceus, Trebouxia spp., Klebsormidium flaccidum, Nephrodiella phaseolus, Navicula pelliculosa and Vischeria magna. In body surface washes, five soil algae species were identified, in gut washes seven algae species were found, while in excretions, just four were observed. It was established that not all algae species from the gut washes of R. kessleri were present in excretions. The presence of some representatives of soil algae, for example, Chlorella vulgaris and Vischeria magna, in natural park litter, body surface washes, gut washes and in excretions of R. kessleri, suggests that the given species pass through the diplopod’s gut and stay undamaged. This indicates that soil saprophage R. kessleri contributes to the dispersal of some soil algae representatives through epi- and endozoochory. Our results represent novel contributions to the knowledge of zoochory. It was shown that animals can be involved in dispersal of not only plant parts but also entire organisms, although it is unknown at what scale diplopods contribute to the diversity and dispersal of algae.

The efficacy of triazavirin (riamilovir)-based treatment for coronavirus disease 2019 (COVID-19) in clinical trials and preliminary practical experiences

Coronavirus disease 2019 (COVID-19) caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has plagued the human population as 2019 turned into 2020, when first cases were confirmed to be infected with the pathogen in Wuhan City, the largest mega-city and capital of Hubei Province in Central China. Since this time, many pharmacotherapeutic modalities were suggested and used to treat the patients suffering from COVID-19. Triazavirin (TZV; riamilovir) is a synthetic non-toxic broad-spectrum antiviral drug belonging into an azolotriazine class. Several hypotheses and suggestions based on the knowledge about morphology, structure of virion, genome, replication cycle and functions of particular proteins within SARS-CoV-2 as well as in silico analyzes were published aiming to employ TZV for the treatment of COVID-19. Results and conclusions from a well-known randomized controlled trial registered under the Registration No. ChiCTR2000030001, which was carried out in China in 2020, indicated not only the anti-SARS-CoV-2 efficacy of given aza analogue of guanine but also some limitations of these outcomes in the context of their general interpretability and applicability. Thus, a primary aim of this review article was to provide more complex view on pharmacotherapeutic interventions based on TZV against COVID-19/SARS-CoV-2. The focus was on relevant results and conclusions from clinical trials as well as practical experiences with given antiviral agent considering not only real benefits of chosen therapeutic strategies but also several obstacles connected with them.

Energy, environmental, resource recovery, and economic dimensions of municipal solid waste management paths in Mexico city.

Growing municipal solid waste (MSW) generation is a source of environmental, economic, and social concerns, especially in developing world megacities where poor MSW practices prevail. Mexico City (CDMX), one of the world's largest megacities, daily produces∼13,073Mg of MSW whose management poses a tremendous challenge to local authorities and calls for additional research to conceive sound MSW strategies. This study evaluates the fossil energy use, GHG emissions, resource recovery, and economic cost dimensions of current and five alternative MSW paths in CDMX to compare their performance and identify more sustainable MSW practices for the megacity. Impacts and benefits from the MSW paths were modeled using 2018 MSW generation data, information supplied by local authorities, and literature values. Current MSW path consumes∼387 MJfossil, generates∼501kg-CO2e, and costs∼57 USD2018 per Mg of MSW managed while it only valorizes<33% of total MSW mostly via informal truck-picking. The alternative MSW paths considerably reduce GHG emissions (∼129-360kg-CO2e/Mg) and enhance MSW valorization (∼47-88%) though, they entail higher fossil energy consumption (447-582 MJfossil/Mg) and, in general, higher cost expenditures (43-208 USD2018/Mg). Heavy reliance on landfilling, large GHG emissions, and low MSW valorization make current MSW path in CDMX unsustainable. Incineration-based MSW paths perform better in most aspects evaluated but their high costs seem prohibitive. Results suggest MSW paths featuring open windrow composting, mechanical-biological pre-treatment, material recovery facilities, and refuse-derived fuel production may be more appropriate to improve the sustainability of CDMX MSW management.

Intra–Community Scale Variability of Air Quality in the Center of a Megacity in South Korea: A High-Density Cost-Effective Sensor Network

To investigate the spatial and temporal variability of air quality (CO, NO2, O3, and PM2.5) with a high spatial resolution in various adjacent micro-environments, 30 sets of sensor-nodes were deployed within an 800 × 800 m monitoring domain in the center of the largest megacity (Seoul) in South Korea. The sensor network was operated in summer and winter. The daily variation in air pollutant concentrations revealed a similar trend, with discernible concentration differences among monitoring sub-sites and a government-operated air quality monitoring station. These differences in pollutant levels (except PM2.5) among the sub-sites were pronounced in the daytime with high volumes of traffic. The coefficient of divergence and Pearson correlation coefficient showed that spatial and temporal variability was more significant in summer than winter. Ozone displayed the greatest spatial variability, with little temporal variability among the sub-sites and a negative correlation with NO2, implying that ozone concentrations were primarily determined by vehicular NOX emissions due to NO titration effects under the urban canopy. The PM2.5 concentration displayed homogeneous spatial and temporal distributions over the entire monitoring period, implying that PM2.5 monitoring with at least a 1 × 1 km resolution is sufficient to examine the spatial and temporal heterogeneity in urban areas.