Soil core study indicates limited CO2 removal by enhanced weathering in dry croplands in the UK

The application of crushed silicate minerals to agricultural soils has been suggested as a route to enhance weathering rates and increase CO2 drawdown. Laboratory studies have attempted to evaluate the potential of enhanced weathering as a CO2 removal technique but do not simulate the geochemical complexity of soil environments, and studies in the field are limited in the nature of data they can collect. To overcome these limitations, this study uses an experimental set-up which fully encapsulates field conditions in a controlled setting using soil cores removed from UK cropland and treated with crushed basalt. Cores were exposed to natural weather conditions throughout a 14-month time series, and soil solution was sampled in 10–20 cm intervals in the core to provide insight into the fate of dissolution products with soil depth. This study assessed the rate and chemistry of basalt dissolution 8 months after addition at a high application rate (100t basalt ha−1) using direct measurements from a UK soil. Assuming conclusions drawn from this study are representative of field-scale enhanced weathering, findings indicate that a set application of basalt to lime-rich, unirrigated UK soils releases alkalinity at a rate of 310 ± 30 eq ha−1 yr−1 and could remove 10.2 ± 0.8 kgCO2 ha−1 yr−1. Accumulation of undissolved basalt may also lead to large and irreversible changes to soil compositions following repeated application. When considering variation in hydrology around the UK, we assess the drawdown potential of application of basalt to all UK arable land as 1.3 ± 0.1 MtCO2 yr−1 which is equivalent to 3% of current UK agricultural CO2 emissions. This is 5- to 25- fold slower than previous modelled assessments, likely due to complexities of soil systems and to water limitation on alkalinity release. Further research is needed to fully assess controls on the potential of enhanced weathering in the real-world environment, across a range of hydrological and soil environments, before the approach is substantively scaled-up for CO2 removal

A Novel Electrical Sensor for Combined Online Measurement of Partial Discharge (OLPD) and Power Quality (PQ)

A novel inductive sensor has been developed that can be used for both for online partial discharge (OLPD) monitoring and power quality (PQ) monitoring. The sensor has been designed for attachment onto power cables with 50/60 Hz currents up to 800 A. The sensor comprises a high frequency (HF) winding to detect partial discharge (PD) pulses between 200 kHz and 30 MHz with a flat frequency response within this range. A low frequency (LF) winding is aimed at monitoring the power frequency (50/60 Hz) and its harmonics up to the 63rd order; it can also be used for current signature analysis (CSA) in rotating machines. A passive low-pass filter is integrated inside the sensor casing to suppress the higher frequencies not relevant to power quality monitoring. The sensor has a split-core design, making it easy to install and allows for retrofit installations. The combined sensor is well suited to places where space is limited such as compact cable boxes where it would be difficult to install two separate sensors. The sensor is primarily used for high voltage (HV) rotating machines (direct or VSD fed) and can be used in a variety of other applications such as monitoring of onshore and offshore wind farms. The paper begins by reviewing the main types of sensors used for partial discharge monitoring followed by the development of the novel sensor. Finally, two case studies where the sensor has been successfully installed are presented

Quantifying CO2 Removal at Enhanced Weathering Sites: a Multiproxy Approach

Enhanced weathering is a carbon dioxide (CO 2) mitigation strategy that promises large scale atmospheric CO 2 removal. The main challenge associated with enhanced weathering is monitoring, reporting, and verifying (MRV) the amount of carbon removed as a result of enhanced weathering reactions. Here, we study a CO 2 mineralization site in Consett, Co. Durham, UK, where steel slags have been weathered in a landscaped deposit for over 40 years. We provide new radiocarbon, δ 13 C, 87 Sr/ 86 Sr, and major element data in waters, calcite precipitates, and soils to quantify the rate of carbon removal. We demonstrate that measuring the radiocarbon activity of CaCO 3 deposited in waters draining the slag deposit provides a robust constraint on the carbon source being sequestered (80% from the atmosphere, 2σ = 8%) and use downstream alkalinity measurements to determine the proportion of carbon exported to the ocean. The main phases dissolving in the slag are hydroxide minerals (e.g., portlandite) with minor contributions (<3%) from silicate minerals. We propose a novel method for quantifying carbon removal rates at enhanced weathering sites, which is a function of the radiocarbon-apportioned sources of carbon being sequestered, and the proportion of carbon being exported from the catchment to the oceans

Mobilisation of arsenic from bauxite residue (red mud) affected soils: effect of pH and redox conditions

The tailings dam breach at the Ajka alumina plant, western Hungary in 2010 introduced ~1 million m3 of red mud suspension into the surrounding area. Red mud (fine fraction bauxite residue) has a characteristically alkaline pH and contains several potentially toxic elements, including arsenic. Aerobic and anaerobic batch experiments were prepared using soils from near Ajka in order to investigate the effects of red mud addition on soil biogeochemistry and arsenic mobility in soil–water experiments representative of land affected by the red mud spill. XAS analysis showed that As was present in the red mud as As(V) in the form of arsenate. The remobilisation of red mud associated arsenate was highly pH dependent and the addition of phosphate to red mud suspensions greatly enhanced As release to solution. In aerobic batch experiments, where red mud was mixed with soils, As release to solution was highly dependent on pH. Carbonation of these alkaline solutions by dissolution of atmospheric CO2 reduced pH, which resulted in a decrease of aqueous As concentrations over time. However, this did not result in complete removal of aqueous As in any of the experiments. Carbonation did not occur in anaerobic experiments and pH remained high. Aqueous As concentrations initially increased in all the anaerobic red mud amended experiments, and then remained relatively constant as the systems became more reducing, both XANES and HPLC–ICP-MS showed that no As reduction processes occurred and that only As(V) species were present. These experiments show that there is the potential for increased As mobility in soil–water systems affected by red mud addition under both aerobic and anaerobic conditions

Zn_2GeO_4/SnO_2 nanowire heterostructures driven by plateau-rayleigh instability

Herein, we report the formation of a particular core-shell structure, with a zinc germanate (Zn_2GeO_4) nanowire core and a discontinuous shell of SnO_2 nanocrystals, obtained in a single-step process. We propose a growth model that combines the Plateau-Rayleigh mechanism to produce a pattern of amorphous germanium oxide (a-GeO_2) particles along the Zn_2GeO_4 nanowire and the subsequent growth of well-faceted SnO_2 crystals when the nanowire orientation meets good lattice matching conditions. In this latter case, the linear array of a-GeO_2 particles acts as nucleation sites for the SnO_2 crystallites, leading to a skewer-like morphology that retains the periodicity of the Plateau-Rayleigh process. Otherwise, nanowires with different orientations appear decorated with a pattern of a-GeO_2 beads mimicking a necklace. Atomic resolution electron microscopy has been used to characterize the Zn_2GeO_4/SnO_2 nanoheterostructures. In addition, optical confinement effects have been observed in the luminescence maps and spectra, which have potential for further exploitation in the design of optical microcavities

Soil-derived Nature’s Contributions to People and their contribution to the UN Sustainable Development Goals

Acknowledgments The input of PS contributes to Soils-R-GRREAT (NE/P019455/1) and the input of PS and SK contributes to the European Union's Horizon 2020 Research and Innovation Programme through project CIRCASA (grant agreement no. 774378). PR acknowledges funding from UK Greenhouse Gas Removal Programme (NE/P01982X/2). GB De Deyn acknowledges FoodShot Global for its support. TKA acknowledges the support of “Towards Integrated Nitrogen Management System (INMS) funded by the Global Environment Facility (GEF), executed through the UK’s Natural Environment Research Council (NERC). The input of DG was supported by the New Zealand Ministry of Business, Innovation and Employment (MBIE) strategic science investment fund (SSIF). PMS acknowledges support from the Australian Research Council (Project FT140100610). PM’s work on ecosystem services is supported by a National Science Foundation grant #1853759, “Understanding the Use of Ecosystem Services Concepts in Environmental Policy”. LGC is funded by National Council for Scientific and Technological Development (CNPq, Brazil – grants 421668/2018-0 and 305157/2018-3) and by Lisboa2020 FCT/EU (project 028360). BS acknowledges support from the Lancaster Environment Centre Project.Peer reviewedPostprin

Transforming U.S. agriculture with crushed rock for CO2_2 sequestration and increased production

Enhanced weathering (EW) is a promising modification to current agricultural practices that uses crushed silicate rocks to drive carbon dioxide removal (CDR). If widely adopted on farmlands, it could help achieve net-zero or negative emissions by 2050. We report detailed state-level analysis indicating EW deployed on agricultural land could sequester 0.23-0.38 Gt CO$_2$ yr$^{-1}$ and meet 36-60 % of U.S. technological CDR goals. Average CDR costs vary between state, being highest in the first decades before declining to a range of $\sim\$$100-150 tCO$_2{}^{-1}$ by 2050, including for three states (Iowa, Illinois, and Indiana) that contribute most to total national CDR. We identify multiple electoral swing states as being essential for scaling EW that are also key beneficiaries of the practice, indicating the need for strong bipartisan support of this technology. Assessment the geochemical capacity of rivers and oceans to carry dissolved EW products from soil drainage suggests EW provides secure long-term CO$_2$ removal on intergenerational time scales. We additionally forecast mitigation of ground-level ozone increases expected with future climate change, as an indirect benefit of EW, and consequent avoidance of yield reductions. Our assessment supports EW as a practical innovation for leveraging agriculture to enable positive action on climate change with adherence to federal environmental justice priorities. However, implementing a stage-gating framework as upscaling proceeds to safeguard against environmental and biodiversity concerns will be essential

Feasibility and results of a randomised pilot-study of pre-discharge occupational therapy home visits

BACKGROUND: Pre-discharge home visits aim to maximise independence in the community. These visits involve assessment of a person in their own home prior to discharge from hospital, typically by an occupational therapist. The therapist may provide equipment, adapt the home environment and/or provide education. The aims of this study were to investigate the feasibility of a randomised controlled trial in a clinical setting and the effect of pre-discharge home visits on functional performance in older people undergoing rehabilitation. METHODS: Ten patients participating in an inpatient rehabilitation program were randomly assigned to receive either a pre-discharge home visit (intervention), or standard practice in-hospital assessment and education (control), both conducted by an occupational therapist. The pre-discharge home visit involved assessment of the older person's function and environment, and education, and took an average of 1.5 hours. The hospital-based interview took an average of 40 minutes. Outcome data were collected by a blinded assessor at 0, 2, 4, 8 and 12 weeks. Outcomes included performance of activities of daily living, reintegration to community living, quality of life, readmission and fall rates. RESULTS: Recruitment of 10 participants was slow and took three months. Observed performance of functional abilities did not differ between groups due to the small sample size. Difference in activities of daily living participation, as recorded by the Nottingham Extended Activities of Daily Living scale, was statistically significant but wide confidence intervals and low statistical power limit interpretation of results. CONCLUSION: Evaluation of pre-discharge home visits by occupational therapists in a rehabilitation setting is feasible, but a more effective recruitment strategy for a main study is favored by application of a multi-centre setting