Green-blue-grey infrastructure (GBGI) offers environmental benefits in urban areas, yet its impact on air pollution is under-researched, and the literature fragmented. This review evaluates quantitative studies on GBGI's capability to mitigate air pollution, compares their specific pollutant removal processes, and identifies areas for further investigation. Of the 51 GBGI types reviewed, only 22 provided quantitative pollution reduction data. Street trees and mixed-GBGI are the most studied GBGIs, with efficacy influenced by wind, GBGI type vegetation characteristics, and urban morphology. Negative percentages denote worsening air quality, while positive reflect improvement. The 22 different GBGI grouped into eight main categories provide an average (± s.d.) reduction in air pollution of 16 ± 21%, with substantial reduction shown by linear features (23 ± 21%), parks (22 ± 34%), constructed GI (14 ± 25%), and other non-sealed urban areas (14 ± 20%). Other individual GBGI reducing air pollutants include woodlands (21 ± 38%), hedges (14 ± 25%), green walls (14 ± 27%), shrubland (12 ± 20%), green roofs (13 ± 23%), parks (9±36%), and mixed-GBGI (7 ± 23 %). On average, GBGI reduced PM1, PM2.5, PM10, UFP and BC by 13 ± 21%, 1 ± 25%, 7 ± 42%, 27 ± 27%, and 16 ± 41%, respectively. GBGI also lowered gaseous pollutants CO, O3 and NOx by 10 ± 21%, 7 ± 21%, and 12 ± 36%, on average, respectively. Linear (e.g., street trees and hedges) and constructed (e.g., green walls) features can impact local air quality, positively or negatively, based on the configuration and density of the built environment. Street trees generally showed adverse effects in street canyons and beneficial outcomes in open-road conditions. Climate change could worsen air pollution problems and impact GBGI effectiveness by shifting climate zones. In Europe and China, climate shifts are anticipated to affect 8 of the 22 GBGIs, with the rest expected to remain resilient. Despite GBGI's potential to enhance air quality, the meta-analysis highlights the need for a standardised reporting structure or to enable meaningful comparisons and effectively integrate findings into urban pollution and climate strategies.
Groundwater dependent terrestrial ecosystems (GWDTEs) face multiple pressures from both atmospheric and terrestrial sources, resulting in the loss of protected habitats and biodiversity. One of the most critical issues facing GWDTEs in England and Wales is anthropogenic pollution from nutrients. Anthropogenic nutrients can originate from a wide range of sources including industry and agriculture, and can be transmitted via multiple pathways including; surface waters, catchment runoff, groundwater, and atmospheric deposition. These multiple pathways pose a problem for environmental regulators and managers. In order to reduce nutrient damage to wetlands, environmental regulators must first have the tools to identify the dominant sources and pathways (source attribution) of nutrients. Environmental regulators need cost effective tools to identify the most common source of nutrients in order to implement effective measures to reduce pressures. However there are a lack of source apportionment studies for GWDTEs, and no framework by which to assess multiple sources of nitrogen. This report aims to bridge that gap by considering both atmospheric and terrestrial sources of nitrogen in one study. Three GWDTEs were studied all characterised during previous Water Framework Directive investigations; Wybunbury Moss, Newbald Becksies and Cors Bodeilio. Each site benefited from existing monitoring data and an evidenced based conceptual model, significantly reducing costs to this project. Field data collection included; inorganic chemistry of groundwater, surface water and rainfall, nitrogen and oxygen isotopes and CFC /SF6 and NH3 /NO2 diffusion tubes deployed to quantify atmospheric dry gaseous deposition. Desk based analysis included; modeled atmospheric source apportionment from www.APIS.ac.uk, catchment nutrient modelling using the ‘Farmscoper’ tool and calculation and comparison of nutrient fluxes against site relevant critical loads from both modeled and measured atmospheric deposition data. We found that; Modelled atmospheric deposition data (www.APIS.ac.uk) was broadly comparable to our monthly on-site data collected at the three GWDTEs, but individual sites showed differing variability in ammonia concentrations compared with the national data. Modeled data provides a reliable way to quickly assess atmospheric loading at GWDTEs for national scale assessments, however site specific assessments should undertake their own measurements of ammonia concentrations. Detailed on site assessments of the pressure from atmospheric deposition to individual habitats are possible using National Vegetation Classification (NVC) mapping combined with Critical Load thresholds and modelled atmospheric deposition. Together these can provide a high resolution picture at site scale, provided vegetation mapping is available Open access modelling tool FarmScoper (ADAS) was successfully applied, however in both examples the modelling shows that even with land use changes the reduction in terrestrial nitrate would not be significant enough to meet the proposed groundwater ‘threshold’ values for nitrate.
Abstract Cultural ecosystem services (CES), a key aspect of nature's contributions to people, remain a challenge to incorporate into decision making. One contributing factor is the difficulty of defining and describing these, due partly to: ongoing poor understanding of what drives people to interact with nature, a lack of appropriate data to quantify these interactions, and basic difficulties in measuring and modelling the complex array of social, psychological and behavioural attributes which help explain people's actions. In this study we present a framework which develops the concepts of cultural capital, social capital and human capital as specific forms of human‐centred capital, in the context of their contribution to understanding CES. Each form of capital encompasses separate attributes of beneficiaries. Testing the framework with data from a separate trans‐disciplinary study illustrated that the framework was readily applicable to specific situations. A measure of cultural capital, EcoCentrism, explained more variation than a suite of seven demographic variables. Applying the framework also showed that despite using a wide range of explanatory variables, a large proportion of observed variation remained unaccounted for. This suggests that more work is needed to understand and to develop metrics which can measure additional factors which underlie peoples’ motivations to engage with nature. The framework is applicable to other types of ecosystem service, and may also be useful for exploring relational values. A free Plain Language Summary can be found within the Supporting Information of this article.