Climate change and urbanization can increase pressures on groundwater resources, but little is known about how groundwater quality will change. Here, we use a global synthesis (n = 9,404) to reveal ...the drivers of dissolved organic carbon (DOC), which is an important component of water chemistry and substrate for microorganisms that control biogeochemical reactions. Dissolved inorganic chemistry, local climate and land use explained ~ 31% of observed variability in groundwater DOC, whilst aquifer age explained an additional 16%. We identify a 19% increase in DOC associated with urban land cover. We predict major groundwater DOC increases following changes in precipitation and temperature in key areas relying on groundwater. Climate change and conversion of natural or agricultural areas to urban areas will decrease groundwater quality and increase water treatment costs, compounding existing constraints on groundwater resources.
Little information is available about the occurrence of neonicotinoid insecticides in surface water and sediment of the metropolitan regions around the rivers in China. Here we investigate the ...residual level of neonicotinoids in the Guangzhou section of the Pearl River. At least one or two neonicotinoids was detected in each surface water and sediment, and the total amount of neonicotinoids (∑5neonics) in surface water ranged from 92.6 to 321 ng/L with a geometric mean (GM) of 174 ng/L. Imidacloprid, thiamethoxam and acetamiprid were three frequently detected neonicotinoids (100%) from surface water. As for the sediment, total concentration was varied between 0.40 and 2.59 ng/g dw with a GM of 1.12 ng/g dw, and acetamiprid and thiacloprid were the common sediment neonicotinoids. Western and Front river-route of the Guangzhou section of the Pearl River suffered a higher neonicotinoids contamination than the Rear river-route, resulting from more effluents of WWTPs receiving, and intensive commercial and human activities. Level of residual neonicotinoids in surface water was significantly correlated with the water quality (p < 0.01), especially items of pH, DO and ORP, and nitrogen and phosphorus contaminants. Compared with reports about residual neonicotinoids in water and sediment previously, the metropolitan regions of the Guangzhou could be confronted with a moderate contamination and showed serious ecological threats (even heavier than the Pearl Rivers). Our results will provide valuable data for understanding of neonicotinoids contamination in the Pearl River Delta and be helpful for further assessing environmental risk of neonicotinoids.
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•Occurrence of neonicotinoids in the Guangzhou section of the Pearl River is examined.•At least one or two neonicotinoids was detected in each water and sediment sample.•IMI, THM and ACE were frequently detected (100%) neonicotinoids from surface water.•Western- and Front-suffered a higher neonicotinoids contamination than Rear river-route.•The Guangzhou section of the Pearl River could be confronted with a moderate neonicotinoid contamination.
This article evaluates the residual level and distribution of neonicotinoids in the Guangzhou section of the Pearl River, South China. It is of great significance to fully understand the migration, transformation, contamination situation and ecological risk of neonicotinoid insecticides.
Urban area definitions are commonly used worldwide to reflect countries’ urban population percentages. The measurements are based on local factors and differ widely across countries, making them ...non-comparable. This is well acknowledged among specialists; however, they are commonly used in everyday practice as universal measurements, and even compared with each other. The problem is that we do not know the degree of error in such comparisons. For this purpose, in the study presented here we analysed and categorised different European national urban area definitions, testing them in the case of Finland. Definitions from 27 European countries were divided into two main categories according to the end result areal unit of the definition and further into seven subcategories based on the criteria used. Thirteen different definitions in the case of Finland were tested using spatial analyses with GIS. The results indicate that urban population percentage varies widely according to different definitions, making their comparability infeasible. The difference is even greater in the case of urban area ratio and population densities of urban areas between the two main categories. The results prove that definitions based on LAU areas cannot illustrate urban areas and their densities coherently. In light of a literature review on certain relational urban area delineation methods and the case study, desirable characteristics for the delineation of urban areas were highlighted. Consequently, a constant, structured evaluation of urbanity measurements and their underlying logic is necessary to enable unambiguous discourse on urban area in urban sciences. The results could help in formulating the applicability of the concept of urban area in scientific and popular communication and media.
•Testing European urban area definitions in Finland resulted in high variation.•Results support the UN guideline not to compare national urban area-based figures.•Administrative units and population alone are insufficient for urban delineation.•Dynamic and relational computational methods reflect better urban systems.•How urban area-related concepts and figures are discussed and used merits consideration.
Potentially Toxic Elements (PTE) are common soil contaminants and pose a significant risk to human health. In this study, ingestion (<150 μm) and inhalation (<10 μm) bioaccessibility and human health ...risk due to PTE were investigated in soils of the urban and peri-urban area of Torino. Lead, Cd, Cu, and Zn were observed to be the most soluble elements in simulated gastric and lung fluids. Higher bioaccessible concentrations of Pb, Ni, Co and Sb were observed in the inhalable size fraction (<10 μm) compared to ingestible one probably because of the higher concentration in fine soil size fraction. Conversely, the relative bioaccessibility of Pb, Cu, Cd, Zn and As was lower, due to the different extracting conditions and to the presumable different elemental speciation. Average values suggested that PTE would be more bioavailable if ingested than inhaled, particularly in urban areas, were the bioaccessible percentages were always higher than in peri-urban sites. Health risk assessment was conducted using bioaccessible concentrations and their corresponding toxicities via ingestion and inhalation exposures. Unacceptable non-carcinogenic risk (HQ > 1) was found through ingestion exposure for children in some urban sites and Pb was the most hazardous elements. Carcinogenic risks were under the threshold levels for every soil (CR < 10−4), with Cr and As being the dominant contributors to risk. Therefore, necessary soil remediation activities are needed to reduce the risks of human, especially for children, exposure to Pb.
•Gastric and lung bioaccessibility in diverse soil size fractions were investigated.•PTE would be more bioavailable if ingested than inhaled.•Higher bioaccessibility was visible in urban sites.•Pb was, still, the most important element for non-carcinogenic risk.
Microplastic (MP) pollution in urban environments is a pervasive and complex problem with significant environmental and human health implications. Although studies have been conducted on MP pollution ...in urban environments, there are still research gaps in understanding the exact sources, regulation, and impact of urban MP on the environment and public health. Therefore, the goal of this study is to provide a comprehensive overview of the complex pathways, harmful effects, and regulatory efforts of urban MP pollution. It discusses the research challenges and suggests future directions for addressing MPs related to environmental issues in urban settings. In this study, original research papers published from 2010 to 2024 across ten database categories, including PubMed, Google Scholar, Scopus, and Web of Science, were selected and reviewed to improve our understanding of urban MP pollution. The analysis revealed multifaceted sources of MPs, including surface runoff, wastewater discharge, atmospheric deposition, and biological interactions, which contribute to the contamination of aquatic and terrestrial ecosystems. MPs pose a threat to marine and terrestrial life, freshwater organisms, soil health, plant communities, and human health through ingestion, inhalation, and dermal exposure. Current regulatory measures for MP pollution include improved waste management, upgraded wastewater treatment, stormwater management, product innovation, public awareness campaigns, and community engagement. Despite these regulatory measures, several challenges such as; the absence of standardized MPs testing methods, MPs enter into the environment through a multitude of sources and pathways, countries struggle in balancing trade interests with environmental concerns have hindered effective policy implementation and enforcement. Addressing MP pollution in urban environments is essential for preserving ecosystems, safeguarding public health, and advancing sustainable development. Interdisciplinary collaboration, innovative research, stringent regulations, and public participation are vital for mitigating this critical issue and ensuring a cleaner and healthier future for urban environments and the planet.
A Graphical summary highlighting microplastics in the urban environment. Display omitted
•Human exposure to urban microplastic (MP) poses significant health concerns.•The treatment of wastewater is necessary prior to disposal to mitigate urban MP.•Urban MP should be addressed to completely fulfill sustainable development goals.•There are now discussions to include MPs in the UN's Sustainable Development Goals.
: The objective of this paper is to analyze social inequalities in COVID-19 incidence, stratified by age, sex, geographical area, and income in Barcelona during the first two waves of the pandemic.
: ...We collected data on COVID-19 cases confirmed by laboratory tests during the first two waves of the pandemic (1 March to 15 July and 16 July to 30 November, 2020) in Barcelona. For each wave and sex, we calculated smooth cumulative incidence by census tract using a hierarchical Bayesian model. We analyzed income inequalities in the incidence of COVID-19, categorizing the census tracts into quintiles based on the income indicator.
: During the two waves, women showed higher COVID-19 cumulative incidence under 64 years, while the trend was reversed after that threshold. The incidence of the disease was higher in some poor neighborhoods. The risk ratio (RR) increased in the poorest groups compared to the richest ones, mainly in the second wave, with RR being 1.67 (95% Credible Interval-CI-: 1.41-1.96) in the fifth quintile income group for men and 1.71 (95% CI: 1.44-1.99) for women.
: Our results indicate the existence of inequalities in the incidence of COVID-19 in an urban area of Southern Europe.
Accurate information on urban areas at regional and global scales is important for both the science and policy-making communities. The Defense Meteorological Satellite Program/Operational Linescan ...System (DMSP/OLS) nighttime stable light data (NTL) provide a potential way to map the extent and dynamics of urban areas in an economic and timely manner. In this study, we developed a cluster-based method to estimate optimal thresholds and map urban extent from the DMSP/OLS NTL data in five major steps, including data preprocessing, urban cluster segmentation, logistic model development, threshold estimation, and urban extent delineation. In our method the optimal thresholds vary by clusters and are estimated based on cluster size and overall nightlight magnitude. The United States and China, two large countries with different urbanization patterns, were selected to test the proposed method. Our results indicate that the urbanized area occupies about 2% of total land area in the US, ranging from lower than 0.5% to higher than 10% at the state level, and less than 1% in China, ranging from lower than 0.1% to about 5% at the province level with some municipalities as high as 10%. The derived thresholds and urban extent were evaluated using a validation sub-sample of high-resolution land cover data at the cluster and regional levels. It was found that our method can map urban areas in both countries efficiently and accurately. The sensitivity analysis indicates that the derived optimal thresholds are not highly sensitive to the parameter choices in the logistic model. Our method reduces the over- and under-estimation issues often associated with previous fixed-threshold techniques when mapping urban extent over a large area. More importantly, our method shows potential to map global urban extent and temporal dynamics using the DMSP/OLS NTL data in a timely, cost-effective way.
•We develop a cluster-based method to map urban extents from nightlight data.•The method performs well in mapping urban extents over large areas.•The method can potentially be used to map global urban areas and temporal dynamics.
Fast advances in autonomous driving technology trigger the question of suitable operational models for future autonomous vehicles. A key determinant of such operational models’ viability is the ...competitiveness of their cost structures. Using a comprehensive analysis of the respective cost structures, this research shows that public transportation (in its current form) will only remain economically competitive where demand can be bundled to larger units. In particular, this applies to dense urban areas, where public transportation can be offered at lower prices than autonomous taxis (even if pooled) and private cars. Wherever substantial bundling is not possible, shared and pooled vehicles serve travel demand more efficiently. Yet, in contrast to current wisdom, shared fleets may not be the most efficient alternative. Higher costs and more effort for vehicle cleaning could change the equation. Moreover, the results suggest that a substantial share of vehicles may remain in private possession and use due to their low variable costs. Even more than today, high fixed costs of private vehicles will continue to be accepted, given the various benefits of a private mobility robot.
•Comprehensive cost analysis of different types of autonomous vehicles.•Market predictions for electrified and/or autonomous vehicles.•Private vehicle ownership will likely endure the rise of such new technologies.•Mass transit likely confined to dense urban areas.•Service costs to be main cost factors of shared autonomous vehicles.
Urban heat island (UHI), the phenomenon that urban areas experience higher temperatures compared to their surrounding rural areas, has significant socioeconomic and environmental impacts. With ...current and anticipated rapid urbanization, improved understanding of the response of UHI to urbanization is important for developing effective adaptation measures and mitigation strategies. Current studies mainly focus on a single or a few big cities and knowledge on the response of UHI to urbanization for large areas is limited. As a major indicator of urbanization, urban area size lends itself well for representation in prognostic models. However, we have little knowledge on how UHI responds to urban area size increase and its spatial and temporal variation over large areas. In this study, we investigated the relationship between surface UHI (SUHI) and urban area size in the climate and ecological context, and its spatial and temporal variations, based on a panel analysis of about 5000 urban areas of 10km2 or larger, in the conterminous U.S. We found statistically significant positive relationship between SUHI and urban area size, and doubling the urban area size led to a SUHI increase as high as 0.7°C. The response of SUHI to the increase of urban area size shows spatial and temporal variations, with stronger SUHI increase in Northern U.S., and during daytime and summer. Urban area size alone can explain as much as 87% of the variance of SUHI among cities studied, but with large spatial and temporal variations. Urban area size shows higher association with SUHI in regions where the thermal characteristics of land cover surrounding the urban area are more homogeneous, such as in Eastern U.S., and in the summer months. This study provides a practical approach for large-scale assessment and modeling of the impact of urbanization on SUHI, both spatially and temporally.
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•We studied relationship between SUHI and urban area size and their spatial and temporal variation in the conterminous U.S.•SUHI increases nonlinearly with the increase of urban area size in a log-linear form.•Doubling urban size increases SUHI as high as 0.7 °C, with larger increase in high latitude areas and in summer and daytime.•Urban area size explains as much as 87% of SUHI variation, with higher value in regions covered by homogenous land cover.
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