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Green roofs (GRs) have been widely adopted as an effective Green Infrastructure (GI) practice in cities worldwide, offering ecosystem services such as stormwater management and reduction of the urban heat island effect. However, their widespread implementation is still limited by a lack of local research and uncertain research findings. As a result, the potential benefits of GRs often cannot justify their high investment costs. Previous studies have sought to enhance the effectiveness of GRs by evaluating new GR systems, such as integrating GRs with green walls, blue roofs, photovoltaic (PV) panels, radiant cooling systems, as well as the use of innovative materials in GR substrates. Biochar, a carbon-rich substrate additive, has been recently investigated. The addition of biochar improves water/nutrient retention of GRs, thereby increasing substrate fertility and promoting plant performance. Although studies have examined the effects of biochar on GR plant growth, long-term observational studies focusing on the impacts of various biochar-related parameters remain necessary. Therefore, this research aims to assess the performance of GR plants with different biochar parameters, namely, amendment rates, application methods, and particle sizes. A one-year-long observational data of plant height, coverage area, and dry weight from six GR test beds was collected and analyzed. Results demonstrate the positive impacts of biochar on plant growth in different biochar-GR setups and types of plant species (wallaby grass, common everlasting, and billy buttons). The GR with medium biochar particles at the amendment rate of 15% v/v had the best plant performance. This contributes to increasing the feasibility of GRs by maximizing GR benefits to buildings where they are installed while reducing GR costs of irrigation and maintenance. The conclusions were further supported by observed data indicating reduced substrate temperature, which in turn reduces building energy consumption. Since vegetation is crucial in determining the effectiveness of a GR system, this study will offer valuable insights to GR designers and urban planners for developing optimal biochar-amended GR systems. Such systems provide numerous benefits over traditional GRs, including enhanced plant growth, reduced building energy costs, a shorter payback period, and reduced structural requirements. [ABSTRACT FROM AUTHOR]

Featured Application: Biochar, a carbon-rich material derived from organic matter through pyrolysis, enhances substrate quality by increasing water retention and nutrient availability, leading to healthier plant growth and increased biodiversity. It also plays a significant role in carbon sequestration, capturing and storing carbon that would otherwise be released into the atmosphere, thus contributing to climate change mitigation efforts. Green roofs (GRs) are a well-established green infrastructure (GI) strategy that have been extensively studied for decades to address a growing array of social and environmental challenges. Research efforts have been continuously made to contribute to the awareness of benefits of GRs and towards their widespread application. The substrate, which is one of the crucial layers of a GR system, plays a major role in the serviceability of GRs. Thus, several studies have been undertaken to alter the substrate characteristics by applying innovative substrate additives. Biochar, a carbon-rich material with a highly porous structure and large specific surface area, has been found advantageous in several areas such as agriculture, water filtration, environmental remediation, construction, and so on. However, the application of biochar in GRs has been insufficiently studied, partially because biochar amendment in GRs is a relatively recent innovation. Furthermore, a comprehensive review of the performance of biochar-amended GR substrates is lacking. This review paper aims to summarize the past performance of GRs enhanced with biochar by considering the various benefits that biochar offers. The results indicate that most of the reviewed studies observed increased retention of runoff and nutrients when utilizing biochar. Additionally, the capabilities of biochar in improving thermal insulation, plant performance, and microbial diversity, as well as its effectiveness in sequestrating carbon and controlling soil erosion, were mostly agreed upon. Notwithstanding, a definitive conclusion cannot yet be confidently made due to the limited research information from biochar–GR systems and the uneven research focus observed in the studies reviewed. The influence of biochar-related variables (including amendment rates, application methods, processed forms, and particle size) on the effectiveness of biochar was also discussed. Opportunities for future research were suggested to fill the research gaps and address challenges restricting the application of biochar in GRs. Detailed information from past research findings could serve as a foundation for further investigations into the large-scale implementation of biochar in GRs. [ABSTRACT FROM AUTHOR]

Green roofs (GRs) are a widely recognized green infrastructure (GI) strategy that helps reduce runoff volume and runoff pollution caused by the significant increase in impervious urban areas. However, the leaching of several nutrients from GR substrates is a growing concern. Biochar, a carbon-rich material, possesses advantageous properties that can help address such environmental challenges associated with GRs. Therefore, this paper aimed to undertake a field study to investigate the impacts of various biochar application methods, particle sizes, and amendment rates on the quality of runoff from GRs. Observational data of runoff quality were collected over a two-month period from five newly established 1 m × 1 m biochar-amended GR test beds and a control test bed without biochar, with all test beds subjected to artificially simulated rainfall. The results indicated that the addition of biochar did not result in a significant improvement in runoff pH, whereas the electrical conductivity (EC) was higher in runoff from GRs with biochar-amended substrates. When comparing the total nitrogen (TN) concentration in runoff from the non-biochar GR (ranging from 3.7 to 31 mg/L), all biochar test beds exhibited higher TN release (4.8 to 58 mg/L), except for the bed where medium biochar particles were applied at the bottom of the substrate (ranging from 2.2 to 21 mg/L). Additionally, all biochar-amended GRs exhibited higher TP concentrations in runoff (0.81 to 2.41 mg/L) when compared to the control GR (0.35 to 0.67 mg/L). Among the different biochar setups, GR with fine biochar particles applied to the surface of the substrate had the poorest performance in improving runoff water quality. Despite these mixed results, biochar holds significant potential to improve runoff quality by significantly increasing water retention, thereby reducing pollutant loads. [ABSTRACT FROM AUTHOR]

We report a 64-year-old male patient without any contributory medical history who visited the eye clinic due to right-sided headache for 1 month and then loss of vision for 3 days. The clinical presentation suggested a cavernous sinus syndrome and acute optic nerve ischaemia in his right eye. The left eye was normal. Orbit and brain magnetic resonance (MR) imaging demonstrated restricted diffusion of the posterior orbital segment of the right optic nerve, suggesting an acute posterior ischaemic optic neuropathy. Three-dimensional time-of-flight MR angiography showed high flow in the right cavernous sinus, indicating a carotid cavernous fistula (CCF). In the arterial phase of digital subtraction angiography (DSA), a fistula in the right cavernous sinus was revealed which was fed by meningeal branches from both the external and internal carotid arteries, confirming an indirect CCF. The origin of the right ophthalmic artery was seen, but its branches were not detected. Right common carotid artery DSA showed a superior ophthalmic vein occlusion and the drainage vein of the CCF ran through the inferior petrosal sinus to the internal jugular vein. The right cavernous sinus was embolised using platinum coils and glue to occlude the feeding vessels from the branches of both the external and internal carotid arteries. Post-embolisation imaging showed complete closure of the fistula. [ABSTRACT FROM AUTHOR]

Water-sensitive urban design (WSUD) has been widely used in cities to mitigate the negative consequences of urbanization and climate change. One of the WSUD strategies that is becoming popular is green roofs (GR) which offer a wide range of ecosystem services. Research on this WSUD strategy has been continuously increasing in terms of both quantity and quality. This paper presents a comprehensive review quantifying the benefits of GRs in papers published since 2010. More precisely, this review aims to provide up-to-date information about each GR benefit and how they have improved over the last decade. In agreement with previous reviews, extensive GRs were considerably researched, as compared to very limited studies on intensive and semi-intensive GRs. Each GR ecosystem service was specifically quantified, and an imbalance of GR research focus was identified, wherein urban heat- and runoff-related benefits were outstandingly popular when compared to other benefits. The results also highlight the recent introduction of hybrid GRs, which demonstrated improvements in GR performance. Furthermore, limitations of GRs, obstacles to their uptake, and inconsistent research findings were also identified in this review. Accordingly, opportunities for future research were pointed out in this review. This paper also recommends future studies to improve upon well-known GR benefits by exploring and applying more innovative GR construction techniques and materials. At the same time, further studies need to be undertaken on inadequately studied GR benefits, such as reduced noise and air pollution. In spite of the existence of reliable modelling tools, their application to study the effects of large-scale implementations of GRs has been restricted. Insufficient information from such research is likely to restrict large-scale implementations of GRs. As a result, further studies are required to transform the GR concept into one of the widely accepted and implemented WSUD strategies. [ABSTRACT FROM AUTHOR]

Competing Interests: The authors report no conflicts of interest.