Passive CO₂ removal in urban soils:evidence from brownfield sites

Management of urban brownfield land can contribute to significant removal of atmospheric CO2 through the development of soil carbonate minerals. However, the potential magnitude and stability of this carbon sink is poorly quantified as previous studies address a limited range of conditions and short durations. Furthermore, the suitability of carbonate-sequestering soils for construction has not been investigated. To address these issues we measured total inorganic carbon, permeability and ground strength in the top 20 cm of soil at 20 brownfield sites in northern England, between 2015 and 2017. Across all sites accumulation occurred at a rate of 1–16 t C ha−1 yr−1, as calcite (CaCO3), corresponding to removal of approximately 4–59 t CO2 ha−1 yr−1, with the highest rate in the first 15 years after demolition. C and O stable isotope analysis of calcite confirms the atmospheric origin of the measured inorganic carbon. Statistical modelling found that pH and the content of fine materials (combined silt and clay content) were the best predictors of the total inorganic carbon content of the samples. Measurement of permeability shows that sites with carbonated soils possess a similar risk of run-off or flooding to sandy soils. Soil strength, measured as in-situ bearing capacity, increased with carbonation. These results demonstrate that the management of urban brownfield land to retain fine material derived from concrete crushing on site following demolition will promote calcite precipitation in soils, and so offers an additional CO2 removal mechanism, with no detrimental effect on drainage and possible improvements in strength. Given the large area of brownfield land that is available for development, the contribution of this process to CO2 removal by urban soils needs to be recognised in CO2 mitigation policies

Sequestering atmospheric CO₂ inorganically:a solution for Malaysia's CO₂ emission

Malaysia is anticipating an increase of 68.86% in CO2 emission in 2020, compared with the 2000 baseline, reaching 285.73 million tonnes. A major contributor to Malaysia's CO2 emissions is coal-fired electricity power plants, responsible for 43.4% of the overall emissions. Malaysia's forest soil offers organic sequestration of 15 tonnes of CO2 ha(-1) year(-1). Unlike organic CO2 sequestration in soil, inorganic sequestration of CO2 through mineral carbonation, once formed, is considered as a permanent sink. Inorganic CO2 sequestration in Malaysia has not been extensively studied, and the country's potential for using the technique for atmospheric CO2 removal is undefined. In addition, Malaysia produces a significant amount of solid waste annually and, of that, demolition concrete waste, basalt quarry fine, and fly and bottom ashes are calcium-rich materials suitable for inorganic CO2 sequestration. This project introduces a potential solution for sequestering atmospheric CO2 inorganically for Malaysia. If lands associated to future developments in Malaysia are designed for inorganic CO2 sequestration using demolition concrete waste, basalt quarry fine, and fly and bottom ashes, 597,465 tonnes of CO2 can be captured annually adding a potential annual economic benefit of (sic)4,700,000.</p

Preface to the Special Issue of Green Mining “Mineral Resources, Mining and Environmental Management in ASEAN”

This issue of Applied Environmental Research includes seven of the papers that were presented at a Regional Workshop on “Mineral Resources, Mining and Environmental Management in ASEAN”, held in Bangkok from 6-8th June, 2013. The theme of the meeting concerned the approach to sustainable mining adopted by the different ASEAN nations that were able to attend, namely Thailand, Laos, Myanmar, Vietnam, and Indonesia, with additional papers from the UK and Germany. An important aspect of the meeting was to compare current practice in individual countries, and this is reflected in the content of the papers published here. Manning’s paper on the situation in the United Kingdom uses case studies to illustrate how the approach to sustainable mining has changed during the last two centuries. A legacy of the consequences of mining over this period has developed into an approach in which mining operations are designed to improve the environment, working with local people from the earliest stage in a project. The design of tailings dams has a major impact on the risk posed by a mining operation, especially following recent dam failures in Hungary and Spain. Coldewey’s paper summarises the key issues relating to the design of tailings dams used to store mine wastes. Much mining in SE Asia involves small scale, artisanal, mines, for which such large facilities are not appropriate. Aung Kyin describes the distribution of artisanal mines in Myanmar, emphasizing the importance of small-scale mining as an employer. Importantly, artisanal mines provide an opportunity to locate and identify targets for large scale mining operations. Kyi Htun goes on to describe the history of mining in Myanmar, with a large number of illustrated examples of current mining operations. The mineral potential of Vietnam is described by Nguyen Ngoc Khoi, who provides a summary of the mined products from Vietnam in the context of the country’s geology. Environmental management of mining is considered in the context of the Lao PDR and Thailand. Phonvisai and Gajaseni summarise the mineral deposits of Lao PDR, and describe the legislative framework that guides environmental monitoring and management. Niyomthai and Wattanawan describe the legacy of problems from past mining in Thailand, and the steps that are being taken to design environmental management protocols that enable mining to take place, while at the same time reassuring the public that environmental harm is minimized. All papers in this special issue address mining within the context of sustainability – social, economic and environmental. The authors come from academic and non-academic backgrounds, and so this collection of papers provides a valuable insight for a wide audience into current thought and practice in this important area. Importantly, mining is essential for sustainable development that helps eliminate poverty and generates employment. It creates wealth that with appropriate management can be used to improve the environment, creating amenities for people affected by mining and remediating the effects of earlier mining activity that might have caused environmental harm.  

Resolving the Conflict between Mining and Sustainability

Mining is essential for human health and prosperity, and is increasing as the global population grows. The need for minerals appears to conflict with what is commonly understood as ‘sustainability’, as geological resources are non-renewable on a human timescale. However, the Brundtland definition of sustainability includes the concept of ‘needs’, implying that there has to be a balanced approach that considers poverty alleviation. It identifies the three pillars of sustainability: economic, social and environmental. In the UK, mining has a legacy extending back over 6000 years. The approach taken to sustainability will be illustrated by 3 examples from northern England. In the 18th and 19th centuries, the London Lead Company was directed by members of the Religious Society of Friends, and had social sustainability as a high priority, building a village with facilities to promote physical, mental and spiritual health amongst the mining community. The legacy of this company’s mining operations on river water pollution is currently a major problem, reflecting its lack of knowledge of geochemistry. Potash mining started in North Yorkshire in the 1960s, and now there are plans for a new potash mine within the North York Moors National Park. Over 1 km deep, the new mine is planned to be as invisible as possible. Open pit coal mining takes place as part of a construction operation in city centre Newcastle, and in nearby rural locations. Operators take great care to minimize their impact on local populations, adapting equipment and making sure operations are timed to minimize disturbance. In the UK, one key characteristic of a successful mining operation is that it engages in dialogue with the local community. It is important to involve the community right from the start of planning a mine, even before its location has been finalized. Operators typically have a community fund, and this can be approached by local people to pay for resources that benefit the community, such as sports equipment and facilities. Mining companies need to have a clear plan for restoration, with dates, and some take the opportunity to plan major works of public art as a way of enriching the community with a legacy that can generate income through tourism

Removal of atmospheric CO₂ by engineered soils in infrastructure projects

The use of crushed basic igneous rock and crushed concrete for enhanced rock weathering and to facilitate pedogenic carbonate precipitation provides a promising method of carbon sequestration. However, many of the controls on precipitation and subsequent effects on soil properties remain poorly understood. In this study, engineered soil plots, with different ratios of concrete or dolerite combined with sand, have been used to investigate relationships between sequestered inorganic carbon and geotechnical properties, over a two-year period. Cone penetration tests with porewater pressure measurements (CPTu) were conducted to determine changes in tip resistance and pore pressure. C and O isotope analysis was carried out to confirm the pedogenic origin of carbonate minerals. TIC analysis shows greater precipitation of pedogenic carbonate in plots containing concrete than those with dolerite, with the highest sequestration values of plots containing each material being equivalent to 33.7 t C ha−1 yr−1 and 17.5 t C ha−1 yr−1, respectively, calculated from extrapolation of results derived from the TIC analysis. TIC content showed reduction or remained unchanged for the top 0.1 m of soil; at a depth of 0.2 m however, for dolerite plots, a pattern of seasonal accumulation and loss of TIC emerged. CPTu tip resistance measurements showed that the presence of carbonates had no observable effect on penetration resistance, and in the case of porewater pressure measurements, carbonate precipitation does not change the permeability of the substrate, and so does not affect drainage. The results of this study indicate that both the addition of dolerite and concrete serve to enhance CO2 removal in soils, that soil temperature appears to be a control on TIC precipitation, and that mineral carbonation in constructed soils does not lead to reduced drainage or an increased risk of flooding

Geotechnical requirements for capturing CO2 through highways land

Roadside verges in Britain support 238,000 hectares of vegetated land and approximately 10 hectares of vegetated central reserves. These areas have the potential to be engineered in such a way that they deliver a range of ecosystem services including flood regulation and biodiversity conservation in addition to their primary functions such as comfort of sidewalk users (mostly un-vegetated), protection of spray from passing vehicles, a space for benches, bus shelters, street lights and other public amenities, and visual improvement of the roads and designated green belts. Previous research has shown that in soils, calcium-rich materials such as recycled crushed concrete or natural crushed dolerite undergo carbonation. This effectively captures CO2 from the atmosphere and stores it in the form of CaCO3 precipitated between soil particles. Engineering this process can potentially assist the UK in achieving its ambitious target to reduce CO2 emissions by 80% of 1990 levels by 2050. Rates of carbonation measured at urban brownfield sites in the UK suggest that treating 12,000 hectares of land containing suitable amendments could remove 1 million tonne CO2 annually. However, brownfield sites are often subjected to re-construction activities which would reduce the rate of CO2 absorption from the atmosphere by sealing. To optimize the rate of carbonation, engineered soils need to be constructed at locations subjected to least post-construction activities and roadside verges and central reserves represent a key opportunity in this regard. This paper calculates limits to CaCO3 formation within the first 1 m of pore spaces of soils at roadside verges and central reserves in Britain considering a soil porosity of 20%

Soil management and engineering for blue-green infrastructure

As urban areas continue to expand, the value of urban blue-green infrastructure (BGI) for increasing the social, environmental and economic sustainability of cities is increasingly recognised. However, there remains an inherent lack of knowledge and awareness around the fundamental contribution that soils make to the functioning of ecosystems within urban BGI. Urban landscapes are a nexus of environmental, engineered and socio-economic factors, which combine to create multifunctional spaces for people to live and work, all underpinned by the soil beneath us. In this chapter, we first outline the characteristics of urban soils and their importance for providing a range of beneficial ecosystem services, such as food production, flood mitigation, carbon storage and opportunities for recreation. We then highlight the key challenges and opportunities around the management and creation of soils within urban BGI. We conclude by emphasising the urgent need for better recognition of urban soils within planning policy and setting out a series of land-use specific management recommendations that will better enable urban soils to support the delivery of ecosystem services and, ultimately, enhance human health and wellbeing

Second to fourth digit ratio (2D:4D) and concentrations of circulating sex hormones in adulthood

<p>Abstract</p> <p>Background</p> <p>The second to fourth digit ratio (2D:4D) is used as a marker of prenatal sex hormone exposure. The objective of this study was to examine whether circulating concentrations of sex hormones and SHBG measured in adulthood was associated with 2D:4D.</p> <p>Methods</p> <p>This analysis was based on a random sample from the Melbourne Collaborative Cohort Study. The sample consisted of of 1036 men and 620 post-menopausal women aged between 39 and 70 at the time of blood draw. Concentrations of circulating sex hormones were measured from plasma collected at baseline (1990-1994), while digit length was measured from hand photocopies taken during a recent follow-up (2003-2009). The outcome measures were circulating concentrations of testosterone, oestradiol, dehydroepiandrosterone sulphate, androstenedione, Sex Hormone Binding Globulin, androstenediol glucoronide for men only and oestrone sulphate for women only. Free testosterone and oestradiol were estimated using standard formulae derived empirically. Predicted geometric mean hormone concentrations (for tertiles of 2D:4D) and conditional correlation coefficients (for continuous 2D:4D) were obtained using mixed effects linear regression models.</p> <p>Results</p> <p>No strong associations were observed between 2D:4D measures and circulating concentrations of hormones for men or women. For males, right 2D:4D was weakly inversely associated with circulating testosterone (predicted geometric mean testosterone was 15.9 and 15.0 nmol/L for the lowest and highest tertiles of male right 2D:4D respectively (<it>P</it>-<it>trend </it>= 0.04). There was a similar weak association between male right 2D:4D and the ratio of testosterone to oestradiol. These associations were not evident in analyses of continuous 2D:4D.</p> <p>Conclusions</p> <p>There were no strong associations between any adult circulating concentration of sex hormone or SHGB and 2D:4D. These results contribute to the growing body of evidence indicating that 2D:4D is unrelated to adult sex hormone concentrations.</p

Mid-life Leukocyte Telomere Length and Dementia Risk: An Observational and Mendelian Randomization Study of 435,046 UK Biobank Participants

Telomere attrition is one of biological aging hallmarks and may be intervened to target multiple aging-related diseases, including Alzheimer\u27s disease and Alzheimer\u27s disease related dementias (AD/ADRD). The objective of this study was to assess associations of leukocyte telomere length (TL) with AD/ADRD and early markers of AD/ADRD, including cognitive performance and brain magnetic resonance imaging (MRI) phenotypes. Data from European-ancestry participants in the UK Biobank (n = 435,046) were used to evaluate whether mid-life leukocyte TL is associated with incident AD/ADRD over a mean follow-up of 12.2 years. In a subsample without AD/ADRD and with brain imaging data (n = 43,390), we associated TL with brain MRI phenotypes related to AD or vascular dementia pathology. Longer TL was associated with a lower risk of incident AD/ADRD (adjusted Hazard Ratio [aHR] per SD = 0.93, 95% CI 0.90–0.96, p = 3.37 × 10−7). Longer TL also was associated with better cognitive performance in specific cognitive domains, larger hippocampus volume, lower total volume of white matter hyperintensities, and higher fractional anisotropy and lower mean diffusivity in the fornix. In conclusion, longer TL is inversely associated with AD/ADRD, cognitive impairment, and brain structural lesions toward the development of AD/ADRD. However, the relationships between genetically determined TL and the outcomes above were not statistically significant based on the results from Mendelian randomization analysis results. Our findings add to the literature of prioritizing risk for AD/ADRD. The causality needs to be ascertained in mechanistic studies