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Food, water, and energy comprise a complex system (FWE nexus) that generates much carbon emissions during operation. At the same time, urban blue-green infrastructure (BGI) has a critical carbon sequestration function. This paper combines the functions of the FWE nexus and BGI and uses ecological network analysis (ENA) and the Markov model to measure the carbon metabolism (CM) mechanisms and evolutionary characteristics of BGI and FWE nexus (BGI-FWE nexus) complex systems. The results show that Guangzhou has high carbon emissions, and Zhaoqing and Huizhou have high carbon sequestration. Resident land and industrial and transportation land transfers to different land uses are more likely to produce positive carbon flows, while BGI transfers to other types are more likely to produce negative carbon flows. The study of CM mechanisms reveals a high proportion of competition relationships and a low proportion of mutualism relationships. The ecological utility index (EUI) tends to fall initially and then increase, peaking at 0.84 in 2015-2020, the highest value for the study period. The CM network has less system robustness (SR) and is in an unsustainable state of high redundancy and low efficiency. The mechanism evolution characterization study's findings show a decreased likelihood of remaining original and less stability in the spatial transfer probability matrices of EUI and SR. In this study, we constructed a BGI-FWE nexus research framework based on the different CM functions of BGI and FWE nexus. The research framework contributes to the realization of carbon reduction in the FWE nexus system and is essential for the planning and management of urban BGI.

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Ecosystem services (ES) are essential to sustainable development at multiple spatial scales. Monitoring ES potential (ESP) at the metropolitan level is imperative to sustainable cities. We developed a procedure for long-term monitoring of metropolitan ESP dynamics, utilizing open-source land use land cover (LULC) data and the expert matrix method. We compared the ESP results of 38 European Capital Metropolitan Areas (ECMA) regarding biodiversity integrity, drinking water provision, flood protection, air quality, water purification, and recreation & tourism. Our results show significant declines in ESP across ECMA due to LULC alteration between 2006, 2012, and 2018. We found that ECMA in post-socialist European countries like Poland (Warszawa) have experienced high rates of land use transformation with a remarkable impact on ESP. Surprisingly, we found that Fennoscandinan ECMA, like Helsinki, Stockholm, and Oslo which lead the cumulative ESP ranking, faced the ESP reduction of the highest impact in recent years. The correlation analysis of ESP dynamics to urban expansion and population growth rates suggests that inattentive urbanization processes impact ESP more than population growth. We unveil the implications of our results to the EU and global level agendas like the European Nature Conservation Law and the Sustainable Development Goals.

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Discourses concerning the potential health benefits of blue-green infrastructure (BGI) have gained momentum, highlighting its positive influence on human health and wellbeing. While studies have explored the concept of "Nature Pyramid" and the role of exposure to natural environments in promoting health, the role of water elements remains underexplored. Rooted in this concept, this study proposed a notion of "blue-green diet" as a framework to understand the intricate mechanisms and determinants of optimal blue-green exposure. Understanding the relationship between these determinants and their health-related impacts can facilitate the enhancement of BGI design, leading to greater effectiveness in promoting health and wellbeing and supporting sustainable urban development strategies. To enhance the comprehension of the "blue-green diet", this study conducted a systematic literature review to grasp the underlying mechanisms behind its beneficial effects, focusing on two key determinants of "blue-green diet", which are also derived from the concept of the "Nature Pyramid": (1) the type of BGI and (2) the mode of interaction with and within BGIs. Under the search of BGI's overall health impacts, this study selected 54 journal publications concerning BGI's type and interaction mode from Web of Science and Scopus since 2010. The review revealed significant disparities in the health benefits provided by different types of BGI (in terms of artificial extent and scale) and between active and passive interaction modes. It examines how to balance natural and artificial elements for enhancing the benefits of BGI and discusses the attributes of BGI that encourage diverse and meaningful interaction patterns. These efforts collectively aim to optimize BGI design and planning, increase its capacity to promote health, and extend its benefits to a wider range of individuals. Future research should encompass a broader spectrum of determinants, such as diverse BGI settings, visit frequency and duration, and user's social-cultural backgrounds.

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Blue-green infrastructure (BGI) plays a crucial role in regulating urban carbon cycles. Nonetheless, the spatiotemporal effect of BGI on carbon emissions has not received extensive attention. This study used the Yangtze River Delta (YRD) region as the study area and quantified the landscape patterns of BGI. Using a spatiotemporal geographically weighted regression model, we analyzed the impact of evolving spatiotemporal characteristics of BGI on carbon emissions. Additionally, we constructed a spatiotemporal weight matrix using the Moran index ratio to examine the spillover effects of BGI among different regions. Our results show that the aggregation effect of carbon emissions in the YRD region is gradually increasing while BGI has a dynamic impact on carbon emissions. In terms of spatial and temporal spillovers, under the influence of economic connections between regions, patch fragmentation and distance exert a persistent positive influence on carbon emissions, while shape complexity has a negative impact, with area and layout characteristics showing no significant effects. However, area and patch distance have a persistent positive influence on carbon emissions in adjacent areas, while shape complexity exhibits a negative impact. Therefore, optimizing urban BGI through a regional synergistic governance system is important to promote low-carbon urban development.

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Sound urban water management relies on extensive and reliable monitoring of water infrastructure. As low-cost sensors and networks have become increasingly available for environmental monitoring, urban water researchers and practitioners must consider the benefits and disadvantages of such technologies. In this perspective paper, we highlight six technical and socio-technological considerations for low-cost monitoring technology to reach its full potential in the field of urban water management, including: technical barriers to implementation, complementarity with traditional sensing technologies, low-cost sensor reliability, added value of produced information, opportunities to democratize data collection, and economic and environmental costs of the technology. For each consideration, we present recent experiences from our own work and broader literature and identify future research needs to address current challenges. Our experience supports the strong potential of low-cost monitoring technology, in particular that it promotes extensive and innovative monitoring of urban water infrastructure. Future efforts should focus on more systematic documenting of experiences to lower barriers to designing, implementing, and testing of low-cost sensor networks, and on assessing the economic, social, and environmental costs and benefits of low-cost sensor deployments.

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Rooftop rainwater harvesting systems and blue-green infrastructure are becoming important resilience alternatives for urban climate adaptation. This study sheds light on the largely unreported physicochemical and microbiological quality of private roof-harvested rainwater (RHRW). We aimed to identify the physicochemical and microbiological characteristics of RHRW, explore potential correlations between them and assess probable health risks associated with recreational interactions of children with the water. RHRW was collected from cisterns and ponds located in an inner courtyard in Hanover, Germany. Physicochemical parameters were measured on site and samples were collected once a month in two campaigns in 2020 and 2021. Escherichia coli concentrations ranged from 1 × 10° to 24.1 × 102 MPN/100 mL, Enterococci from 1 × 10° to 19.7 × 102 MPN/100 mL, Salmonella from 1 × 102 to 39 × 103 CFU/100 mL and Pseudomonas aeruginosa from 1 × 10° to 3 × 103 MPN/100 mL. Correlation analysis indicated potential relationships between bacteria, oxygen, and water temperature. The results of the health risk assessment indicated a potential risk of gastrointestinal illnesses due to exposure to Enterococci and Salmonella spp. present in the cisterns and ponds, highlighting the need for appropriate regulations and guidelines for RHRW aimed for non-potable uses. Blue-green infrastructure, when effectively managed and maintained, can offer benefits both by enhancing urban climate resilience and promoting citizens well-being.

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Urban floods will continue to be an alarming issue worldwide due to climate change and urban expansion. The costly and less environmentally friendly grey infrastructure is not always the most adequate solution to resolve urban pluvial flooding issues. The combination of grey and blue-green infrastructures, also called hybrid infrastructure, has been considered a promising solution for urban stormwater management. Existing approaches for identifying suitable hybrid solutions frequently rely on global multi-objective optimization algorithms. We developed a pre-screening method that decomposes a drainage network into clusters of pipes connected to sub-catchments, based on pipe hydraulic characteristic that allows for the impact of infrastructure combinations (blue-green and grey) to be mapped. Four impact matrices are proposed to map the total, local, upstream, and downstream flood reduction of all possible blue-green, grey, and hybrid solutions. Using an urban catchment in Guangzhou (China) as a case study, results showed that such an exercise could identify prime candidate locations for blue-green and grey infrastructure while filtering out ineffective locations for flood reduction. Furthermore, the impact matrices enabled the identification of flood zones where blue-green infrastructure could handle flood mitigation without the need of local grey infrastructure upgrades. As such, they are not only useful for quick screening of suitable interventions for each flooded zone, but can also potentially serve as a priori knowledge before diving into the data and computationally expensive process of finding the most effective flood mitigation solutions.

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Seagrass meadows provide several ecological functions that improve the overall ecological health of coastal systems and therefore, it is urgent to promote the restoration of such habitats. In Ria de Aveiro, a coastal lagoon in the Atlantic Coast of Portugal, a restoration initiative was responsible for transplanting the dwarf eelgrass Zostera noltei into a highly degraded area. This eelgrass was used as a nature-based solution (NbS) to mitigate some of the impacts of historical mercury contamination. Comparisons of key-species features (density and biomass), and some community-derived indicators (total density and biomass, species richness and Shannon-Wiener index) between the transplanted seagrass patch, their bare vicinities, and their counterpart habitats on the source area, provided signs of the effectiveness of the restoration action on the benthic communities' recovery. Indicators were higher within the restored meadow, and biomass derived indicators of the restored meadow were similar to the source meadow.

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Small waterbodies such as ponds are widely represented in cities, contributing to the blue-green infrastructure, improving human well-being. Ornamental ponds are particularly abundant in the densest urbanized areas, especially in parks, in private grounds such as gardens and also imbedded in the green infrastructure. However, their multifunctionality remains infrequent, as generally aesthetic enjoyment is the main ecosystem service targeted. The promotion of native biodiversity is rarely a priority, as are other ecosystem services (e.g. flood mitigation or water purification). It is nevertheless questionable if such mono-functional ponds could also be able to provide other services. Indeed, an innovative approach would be to increase the multifunctionality of ornamental ponds, especially for biodiversity. This was investigated in 41 ornamental ponds designed for providing aesthetic enjoyment in the city of Geneva (Switzerland). The biodiversity was assessed, as well as selected ecosystem services (water retention, phytopurification, cooling effect, carbon sequestration). A survey among the population was also conducted. This survey underlined a recognized contribution of ornamental ponds to well-being. However, the assessment of the ecosystem services evidenced a lack of multifunctionality for most of these ponds. They presented a low biodiversity, compared to more natural ponds and to unimpaired ponds. Furthermore, they performed poorly for most other ecosystem services investigated. There were nevertheless exceptions, with selected ponds displaying a multifunctionality, even for ecosystem services for which they were not designed. It was also shown that ornamental ponds could easily be optimized for biodiversity by simple low-cost management measures. Additional ecosystem services could also be promoted. The performance of small ornamental ponds is best when ponds are considered collectively, as pondscapes, with their cumulative benefits. New ornamental pond implementation is therefore encouraged, as their multifunctionality turns them into Nature-based Solutions able to contribute to solving several societal challenges and to improve human well-being.

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Blue-green infrastructure provides a variety of ecosystem services and is becoming an increasingly vital part of urban ecosystem protection. It is an ecological facility for ecological conservation and environmental protection, and a foundation for realizing people's needs for a better life. This study selects indicators from four dimensions: social, economic, environmental, and ecological, and the demand for blue-green infrastructure is assessed comprehensively. The results show that: (1) the demand for blue-green infrastructure varies spatially with the development of the city; (2) the total demand for blue-green infrastructure in Nanjing from 2000 to 2020 shows a pattern of "high in the center and low in the periphery"; (3) the level of economic development, urban spatial pattern, and decision management orientation have different degrees of influence on the demand for blue-green infrastructure, with the urban spatial pattern having the greatest impact. Therefore, in the future, blue-green infrastructure should be optimized by taking into account the spatial characteristics of demand in Nanjing.

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Land use/land cover (LULC) changes and high urbanization rates are the main drivers of avian habitat loss in developing countries. However, few studies have examined the effects of urbanization intensity on avian diversity distribution and its importance in guiding eco-friendly urban planning. We surveyed bird distribution (n = 67 species) in different seasons using local ecological knowledge (LEK) and transect line methods in Jiangyan District from July 2018 to May 2019. One-way analysis of variance (ANOVA) was used to assess the effects of urbanization levels on birds relative density and richness during spring-summer (breeding season) and autumn-winter seasons (non-breeding season). Generalized linear models (GLM) were identified for the landscape composition and configuration that drive relative density and richness in native bird communities. Using redundancy analysis (RDA), we identified the landscape composition and configuration factors affecting bird foraging and roosting at urbanization levels. The results showed high dependency of waders and granivores on paddy fields and dry arable land respectively during the breeding season. During non-breeding season, wetland abundance, land cover, connectivity and total area of BGI were important habitat factors in attracting birds. Moreover, the landscape composition and configuration factors of BGI: wetlands as well as farmland habitats, are the main environmental cues that influence bird foraging. Therefore, to increase habitat suitability over landscape matrix, we propose creation of multiple waterbodies and green corridors of variable types and sizes on natural patches to improve the connectivity of ecological network. We also recommend land management interventions in farmland ecosystems, which could contribute to natural habitat restoration and improve bird biodiversity in urban areas.

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Since the needs and expectations of communities towards their urban environments often vary, landscape management strategies can often be prone to fail in the absence of social considerations. It is therefore incumbent on policy-makers to investigate and attempt to reconcile diverse community perceptions toward the natural and built environment for more equitable governance. This is of particular interest when planning and managing nature-based solutions (NBS) for river protection. We considered this challenge in understanding human values, perceptions and behaviour in a multilayered ecosystem that includes waterways, NBS, green open spaces, and a built environment. This paper analyses perceptions and behaviour around a public urban park next to the Georges River in Sydney Australia, utilizing a proxy-based approach and a mixed-method comprising community surveys and behavioural mapping. The results showed that while users perceive the significance of the urban river environment differently, naturalistic (ecological), humanistic (recreational) and utilitarian (well-being) values are dominant. Urban river catchments are highly valued for recreational purposes, with a strong perception of potential flooding hazards. Through exploring the literature, we recognized that the dominancy of leisure-related values around urban river catchments can be generalized to similar cases worldwide. While NBS, as an urban stormwater management solution, address some user values (e.g., naturalistic) around urban river catchments, they may lack further delivery of humanistic and utilitarian values due to the poor integration with recreational and cultural spaces. It was also the case around the Georges River, where low prominence of cultural features was observed. We concluded that NBS development around Georges River and other urban river catchments should incorporate socio-cultural considerations and community values, in particular the ones related to leisure. The gaps between users' beliefs and behaviour do not greatly challenge governance, provided that the decision-makers utilise these gaps for optimising management actions.

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More than half of new urban residential developments are planned as infill in Australia's major cities. This provides an unprecedented opportunity to use innovative design and technology to address urban water challenges such as flooding, reduced water security and related infrastructure and urban heat island issues. However, infill can have positive or negative water impacts, depending on architectural design and on-site water servicing technologies implemented. In this study we asked, "What influence does residential infill development have on the local urban water cycle?" and "What roles do architectural design and technologies play?" To answer these questions, a set of 196 design-technology configurations were developed by combining 28 architectural designs and 7 on-site water-servicing technology options. The configurations represent three cases: (i) existing (EX) or before infill, (ii) business-as-usual development (BAU), and (iii) alternative development (ALT). Using the Site-scale Urban Water Mass Balance Assessment (SUWMBA) model and a set of water performance indicators, the impact of configurations on the urban water cycle was quantified. The results showed BAU, on average, increases population density, stormwater discharge, and imported water by 98%, 44% and 85%, and decreases evapotranspiration and infiltration by 53% and 34%, compared to the EX conditions. More population density (141%) with lower impacts on the urban water cycle (21% and 64% increase for stormwater discharge and imported water, and 29% and 17% reduction in evapotranspiration and infiltration) can be achieved by appropriate integration of ALT designs and technologies. Architectural design has a greater influence on urban water flows than the implementation of on-site water servicing technologies. The results have a great implication for sustainable urban water management for managing the risks associated with pluvial flooding, water insecurity, and urban heat. It also highlights the underutilised role of architects and urban planners to address urban water issues.

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Spatial planning of Blue-Green Infrastructure (BGI) should ideally be based on well-evaluated and context specific solutions. One important obstacle to reach this goal relates to adequate provisioning of data to ensure good governance of BGI, i.e., appropriate planning, design, construction, and maintenance. This study explores the gap between data availability and implementation of BGI in urban planning authorities in Sweden. A multi method approach including brainstorming, semi-structured interviews with urban planners and experts on BGI and Geographical Information System (GIS), and validating workshops were performed to develop a framework for structured and user-friendly data collection and use. Identified challenges concern data availability, data management, and GIS knowledge. There is a need to improve the organisation of data management and the skills of trans-disciplinary cooperation to better understand and interpret different types of data. Moreover, different strategic goals require different data to ensure efficient planning of BGI. This calls for closer interactions between development of strategic political goals and data collection. The data management framework consists of three parts: A) Ideal structure of data management in relation to planning process, data infrastructure and organisational structure, and B) A generic list of data needed, and C) The development of structures for data gathering and access. We conclude that it is essential to develop pan-municipal data management systems that bridge sectors and disciplines to ensure efficient management of the urban environment, and which is able to support the involvement of citizens to collect and access relevant data. The framework can assist in such development.

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Urban Heat Island (UHI) effect relates to the occurrence of a positive heat balance, compared to suburban and extra-urban areas in a high degree of urbanized cities. It is necessary to develop effective UHI prevention and mitigation strategies, one of which is blue-green infrastructure (BGI). Most research work comparing impact of BGI parameters on UHI mitigation is based on data measured in different climate zones. This makes the implication of nature-based solutions difficult in cities with different climate zones due to the differences in the vegetation time of plants. The aim of our research was to select the most statistically significant quality parameters of BGI elements in terms of preventing UHI. The normative four-step data delimitation procedure in systematic reviews related to UHI literature was used, and temperate climate (C) zone was determined as the UHI crisis area. As a result of delimitation, 173 publications qualified for literature review were obtained (488 rejected). We prepared a detailed literature data analysis and the CVA model-a canonical variation of Fisher's linear discriminant analysis (LDA). Our research has indicated that the BGI object parameters are essential for UHI mitigation, which are the following: area of water objects and green areas, street greenery leaf size (LAI), green roofs hydration degree, and green walls location. Data obtained from the statistical analysis will be used to create the dynamic BGI modeling algorithm, which is the main goal of the series of articles in the future.

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In 2019 floods made up 49 % of disasters and 43 % of disaster related deaths globally. Flooding is also the costliest natural disaster, with yearly estimated losses of $36.3 billion. In order to counter these challenges, the flood risk management (FRM) narrative is evolving towards integration of blue/green infrastructure (BGI), using projects that harness nature and mimic natural processes. However, there is very little research into how BGI-related innovations will be mainstreamed, nor, particularly, how they will be funded. In order to reflect upon this situation, this paper analyses current academic literature and international best practice in BGI and Land Value Capture (LVC) instruments - to form a novel conceptual framework that is designed to act as a staging post for new research into BGI and its practical delivery. Specifically, this analysis focuses on the Transferable Development Rights (TDR) instrument, which has enabled some planning authorities to successfully push forward their environmental agendas, through land conservation, including in flood prone areas. This gap in knowledge has multiple significance. Firstly, land management decisions related to BGI can have deep distributive-justice implications that need to be addressed. Secondly, there is an immediate need to pay for such FRM measures across the world. Thirdly, this financial imperative takes place against an international backdrop of reduced government funding in a time of deep structural change and Covid-19 pressure. Findings in this paper suggest that TDR has the potential to be a successful conduit for managing all three conditions. Yet, the success of TDR is closely linked to the specific legal, market and urban development contexts, which further research should explore within the framework of BGI implementation.

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Understanding public perceptions of Sustainable Drainage Systems (SuDS) is critical for addressing barriers to their implementation. Perceptions are typically evaluated using explicit measures (e.g. questionnaires) that are subject to biases and may not fully capture attitudes towards SuDS. A novel image-based application of the Implicit Association Test is developed to investigate unconscious perceptions of SuDS in public greenspace and combined with explicit tests to evaluate perceptions of greenspace with and without SuDS, focusing on a sample population in Newcastle-upon-Tyne. Greenspace with or without SuDS is perceived positively by the sample population. Overall, respondents implicitly and explicitly prefer greenspace without SuDS and perceive greenspace without SuDS as more attractive, tidier and safer. The wide distribution of scores for SuDS, nonetheless, suggests a range of opinions and illustrates the complex nature of preferences for the use of greenspace. That the strongly negative explicit scores were not reflected in the implicit tests may suggest that explicit attitudes towards tidiness and safety may not be deep-rooted and are subject to social bias. Combined explicit and implicit tests may help us to understand any disconnect between expressed positive attitudes to natural spaces and behaviours around them and inform SuDS design to increase public acceptance. This article is part of the theme issue 'Urban flood resilience'.

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The use of stormwater biofilters (also known as bioretention systems and raingardens), in tropical and semi-arid areas is hindered by seasonal rainfall patterns which cause extended dry periods. These periods can result in plant die-off, long-term damage to system health and leaching of pollutants when stormwater inflows resume. Using an additional polluted water source during dry periods could minimise system stress and eliminate the need to irrigate biofilters with potable water during dry spells. As such, the presented laboratory study tested the seasonal operation of biofilters, by switching from stormwater treatment in wet months to greywater treatment in dry months. Forty-five single planted biofilter columns, incorporating sedges, grasses, understory ornamentals and vines, were subjected to four months of stormwater inflows, followed by three months of greywater inflows. We also investigated the impact of including a carbon source in the saturated zone on treatment performance. The results showed plant species selection to be critical for nitrogen and phosphorus removal, with consistently effective species such as Carex appressa and Canna x generalis able to maintain low outflow concentrations (e.g. total nitrogen of 0.2-0.3 mg/L and 0.3-0.6 mg/L, respectively) across both water sources. Low outflow phosphorus concentrations were associated with plant species that had high filterable reactive phosphorus removal across both water sources. Similarly, higher removal of ammonia and oxidised nitrogen was associated with lower overall nitrogen concentrations. In contrast, high removal of total suspended sediment (>94%), biochemical oxygen demand (>98%) and some heavy metals (e.g. lead >98% and copper >93%) was reported across all designs. The results suggest that with the careful selection of plant species, biofilters can be operated seasonally as a feasible and practical solution to maintaining system health during extended dry periods.

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Improved nature provision in urban environments offers great potential for achieving both biodiversity conservation and public health objectives. Yet there are few experimental studies that address links between specific natural environments and physiological and/or psychological changes that could contribute to the health and wellbeing co-benefits of urban nature. In addition, relative to green space, the salutogenic impact of aquatic environments are understudied. Here, we present a feasibility study examining the use of low-cost wearable technology to quantify the psychophysiological effects of short-term exposure to urban wetlands. The study took place at the WWT London Wetland Centre, which is characterized by its contrasting biodiverse wetland habitat and surrounding urban setting. Thirty-six healthy participants experienced counterbalanced exposures to an indoor space, a wetland, an urban site. We continuously recorded electroencephalographic (EEG) data and real-time physiological stress responses; with additional monitoring of post-exposure self-reported mood states. We found a significant effect of site on mean resting heart rate (HR), with increased HR in the urban setting, although this was only observed in participants with pre-existing high stress. We found no significant differences in other measures of physiological stress responses (heart rate variability and electrodermal activity). The EEG data showed modulation of high beta band activity only in the wetland setting, potentially related to changes in attention. However, the EEG findings were confounded by low quality signals and artifacts caused by movement and environmental interference. Assessments of self-reported mood states demonstrated an increase in positive feelings in the wetland setting. A pronounced decrease in negative feelings in the wetland setting was observed in stressed individuals only. Our results suggest that pre-existing stress levels may be an important modulator of the salutogenic effect of blue-green space. We provide partial support for the hypothesis that exposure to blue-green space promotes stress recovery and for the use of low-cost psychophysiological measurements to quantify the potential stress-reducing effects of blue-green space exposure in urban dwellers. Further technological refinement is required for this approach to become a viable tool to support evidence-based decision-making for public health and green/blue space provision.

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Growing interest in the concept of nature-based solutions (NBS) raises the question of its applicability as a broadly-understood approach to resource management and spatial planning. Although both the European Commission and United Nations consider the use of NBS as a vehicle to achieve numerous sustainability goals, the concept itself remains under-defined. We analyse the NBS concept against the background of classical water-ecosystem theories. We also review a range of potential contributions by NBS to various aspects of city management, resilience and adaptation. Finally we introduce the concept of a continuum of ecosystem service transfer across city management zones, with NBS acting as the medium, minimizing the net loss of regulatory services, and optimizing the cost-efficiency of solutions. We summarize with analysis of existing best practices in urban water management from the perspective of utilizing natural processes according to the supply and demand of services, and with a threefold target: enabling, restoring or preserving nature.