Sensitivity of mid-19th century tropospheric ozone to atmospheric chemistry-vegetation interactions

We use an Earth-System model (HadGEM2-ES) to investigate the sensitivity of mid-19th century tropospheric ozone to vegetation distribution and atmospheric chemistry-vegetation interaction processes. We conduct model experiments to isolate the response of mid-19th century tropospheric ozone to vegetation cover changes between the 1860s and present-day and to CO2 induced changes in isoprene emissions and dry deposition over the same period. Changes in vegetation distribution and CO2 suppression of isoprene emissions between mid-19th century and present-day, lead to decreases in global isoprene emissions of 19% and 21% respectively. This results in increases in surface ozone over the continents of up to 2 ppbv and of 2-6 ppbv in the tropical upper troposphere. The effects of CO2 increases on suppression of isoprene emissions and suppression of dry deposition to vegetation are small compared with the effects of vegetation cover change. Assuming present-day climate in addition to present-day vegetation cover and atmospheric CO2 concentrations, leads to increases in surface ozone concentrations of up to 5 ppbv over the entire northern hemisphere (NH), and of up to 8 ppbv in the NH free troposphere, compared with a mid-19th century simulation. Ozone changes are dominated by: 1) the role of isoprene as an ozone sink in the low NOx mid-19th century at30 mosphere, and 2) the redistribution of NOx to remote regions and the free troposphere via PAN (peroxyacetyl nitrate) formed from isoprene oxidation. We estimate a tropospheric ozone radiative forcing of 0.264W m−2 and a sensitivity in ozone radiative forcing to mid-19th century to present-day vegetation cover change of -0.012W m−2

A Probabilistic Assessment of the COVID-19 Lockdown on Air Quality in the UK

In March 2020 the United Kingdom (UK) entered a nationwide lockdown period due to the Covid-19 pandemic. As a result, levels of nitrogen dioxide (NO2) in the atmosphere dropped. In this work, we use 550,134 NO2 data points from 237 stations in the UK to build a spatiotemporal Gaussian process capable of predicting NO2 levels across the entire UK. We integrate several covariate datasets to enhance the model's ability to capture the complex spatiotemporal dynamics of NO2. Our numerical analyses show that, within two weeks of a UK lockdown being imposed, UK NO2 levels dropped 36.8%. Further, we show that as a direct result of lockdown NO2 levels were 29-38% lower than what they would have been had no lockdown occurred. In accompaniment to these numerical results, we provide a software framework that allows practitioners to easily and efficiently fit similar models

The TOMCAT global chemical transport model v1.6: description of chemical mechanism and model evaluation

This paper documents the tropospheric chemical mechanism scheme used in the TOMCAT 3-D chemical transport model. The current scheme includes a more detailed representation of hydrocarbon chemistry than previously included in the model, with the inclusion of the emission and oxidation of ethene, propene, butane, toluene and monoterpenes. The model is evaluated against a range of surface, balloon, aircraft and satellite measurements. The model is generally able to capture the main spatial and seasonal features of high and low concentrations of carbon monoxide (CO), ozone (O3), volatile organic compounds (VOCs) and reactive nitrogen. However, model biases are found in some species, some of which are common to chemistry models and some that are specific to TOMCAT and warrant further investigation. The most notable of these biases are (1) a negative bias in Northern Hemisphere (NH) winter and spring CO and a positive bias in Southern Hemisphere (SH) CO throughout the year, (2) a positive bias in NH O3 in summer and a negative bias at high latitudes during SH winter and (3) a negative bias in NH winter C2 and C3 alkanes and alkenes. TOMCAT global mean tropospheric hydroxyl radical (OH) concentrations are higher than estimates inferred from observations of methyl chloroform but similar to, or lower than, multi-model mean concentrations reported in recent model intercomparison studies. TOMCAT shows peak OH concentrations in the tropical lower troposphere, unlike other models which show peak concentrations in the tropical upper troposphere. This is likely to affect the lifetime and transport of important trace gases and warrants further investigation

Prediction of storm transfers and annual loads with data-based mechanistic models using high-frequency data

Excess nutrients in surface waters, such as phosphorus (P) from agriculture, result in poor water quality, with adverse effects on ecological health and costs for remediation. However, understanding and prediction of P transfers in catchments have been limited by inadequate data and over-parameterised models with high uncertainty. We show that, with high temporal resolution data, we are able to identify simple dynamic models that capture the P load dynamics in three contrasting agricultural catchments in the UK. For a flashy catchment, a linear, second-order (two pathways) model for discharge gave high simulation efficiencies for short-term storm sequences and was useful in highlighting uncertainties in out-of-bank flows. A model with nonlinear rainfall input was appropriate for predicting seasonal or annual cumulative P loads where antecedent conditions affected the catchment response. For second-order models, the time constant for the fast pathway varied between 2 and 15 h for all three catchments and for both discharge and P, confirming that high temporal resolution data are necessary to capture the dynamic responses in small catchments (10–50 km2/. The models led to a better understanding of the dominant nutrient transfer modes, which will be helpful in determining phosphorus transfers following changes in precipitation patterns in the future

Simulated global climate response to tropospheric ozone-induced changes in plant transpiration

Tropospheric ozone (O₃) pollution is known to damage vegetation, reducing photosynthesis and stomatal conductance, resulting in modified plant transpiration to the atmosphere. We use an Earth system model to show that global transpiration response to near‐present‐day surface tropospheric ozone results in large‐scale global perturbations to net outgoing long‐wave and incoming shortwave radiation. Our results suggest that the radiative effect is dominated by a reduction in shortwave cloud forcing in polluted regions, in response to ozone‐induced reduction in land‐atmosphere moisture flux and atmospheric humidity. We simulate a statistically significant response of annual surface air temperature of up to ~ +1.5 K due to this ozone effect in vegetated regions subjected to ozone pollution. This mechanism is expected to further increase the net warming resulting from historic and future increases in tropospheric ozone

Determining the effect of drying time on phosphorus solubilization from three agricultural soils under climate change scenarios

Climate projections for the future indicate that the United Kingdom will experience hotter, drier summers and warmer, wetter winters, bringing longer dry periods followed by rewetting. This will result in changes in phosphorus (P) mobilization patterns that will influence the transfer of P from land to water. We tested the hypothesis that changes in the future patterns of drying–rewetting will affect the amount of soluble reactive phosphorus (SRP) solubilized from soil. Estimations of dry period characteristics (duration and temperature) under current and predicted climate were determined using data from the UK Climate Projections (UKCP09) Weather Generator tool. Three soils (sieved 25°C are predicted in some places and dry periods of 30 to 90 d extremes are predicted. Combining the frequency of projected dry periods with the SRP concentration in leachate suggests that this may result overall in increased mobilization of P; however, critical breakpoints of 6.9 to 14.5 d dry occur wherein up to 28% more SRP can be solubilized following a rapid rewetting event. The precise cause of this increase could not be identified and warrants further investigation as the process is not currently included in P transfer models

Produtos de hidratação em argamassas geopoliméricas à base de argila da Tunísia para reparação de estruturas de concreto

A reparação de estruturas degradadas de concreto representa uma oportunidade para a indústria da construção mas também um desafio para a comunidade científica. O desenvolvimento de novas argamassas de reparação constitui por isso uma importante área de investigação. Os geopolímeros são ligantes inovadores alternativos ao cimento Portland pelo que as argamassas à base destes materiais, geopolíméricas, apresentam algumas potencialidades no campo da reparação das estruturas de concreto. O presente artigo apresenta resultados de uma investigação sobre o desenvolvimento de argamassas geopoliméricas à base de uma argila da Tunísia sujeita a tratamento térmico. É incluída uma análise da argila e também dos produtos de hidratação da argamassa os quais apresentam fases geopoliméricas típicas

Legal origin and social solidarity: the continued relevance of Durkheim to comparative institutional analysis

By using the classic works of Durkheim as a theoretical platform, this research explores the relationship between legal systems and social solidarity. We found that certain types of civil law system, most notably those of Scandinavia, are associated with higher levels of social capital and better welfare state provision. However, we found the relationship between legal system and societal outcomes is considerably more complex than suggested by currently fashionable economistic legal origin approaches, and more in line with the later writings of Durkheim, and, indeed, the literature on comparative capitalisms. Relative communitarianism was strongly affected by relative development, reflecting the complex relationship between institutions, state capabilities and informal social ties and networks

Crop Updates 2006 - Weeds

This session covers thirty seven papers from different authors: 1. ACKNOWLEDGEMENTS, Alexandra Douglas, CONVENOR – WEEDS DEPARTMENT OF AGRICULTURE SPRAY TECHNOLOGY 2. Meeting the variable application goals with new application technology, Thomas M. Wolf, Agriculture and Agri-Food Canada, Saskatoon Research Centre 3. Spray nozzles for grass weed control, Harm van Rees, BCG (Birchip Cropping Group) 4. Boom sprayer setups – achieving coarse droplets with different operating parameters, Bill Gordon, Bill Gordon Consulting 5. Complying with product label requirements, Bill Gordon, Bill Gordon Consulting 6. IWM a proven performer over 5 years in 33 focus paddocks, Peter Newman and Glenn Adam, Department of Agriculture 7. Crop topping of wild radish in lupins and barley, how long is a piece of string? Peter Newman and Glenn Adam, Department of Agriculture 8. Determining the right timing to maximise seed set control of wild radish, Aik Cheam and Siew Lee, Department of Agriculture 9. Why weed wiping varies in success rates in broadacre crops? Aik Cheam1, Katherine Hollaway2, Siew Lee1, Brad Rayner1 and John Peirce1,1Department of Agriculture, 2Department of Primary Industries, Victoria 10. Are WA growers successfully managing herbicide resistant annual ryegrass? Rick Llewellynabc, Frank D’Emdena, Mechelle Owenb and Stephen Powlesb aCRC Australian Weed Management, School of Agricultural and Resource Economics, University of Western Australia; bWA Herbicide Resistance Initiative, University of Western Australia. cCurrent address: CSIRO Sustainable Ecosystems 11. Do herbicide resistant wild radish populations look different? Michael Walsh, Western Australian Herbicide Resistance Initiative, University of Western Australia 12. Can glyphosate and paraquat annual ryegrass reduce crop topping efficacy? Emma Glasfurd, Michael Walsh and Kathryn Steadman, Western Australian Herbicide Resistance Initiative, University of Western Australia 13. Tetraploid ryegrass for WA. Productive pasture phase AND defeating herbicide resistant ryegrass, Stephen Powlesa, David Ferrisab and Bevan Addisonc, aWA Herbicide Resistance Initiative, University of Western Australia; bDepartment of Agriculture, and cElders Limited 14. Long-term management impact on seedbank of wild radish with multiple resistance to diflufenican and triazines, Aik Cheam, Siew Lee, Dave Nicholson and Ruben Vargas, Department of Agriculture 15. East-west crop row orientation improves wheat and barley yields, Dr Shahab Pathan, Dr Abul Hashem, Nerys Wilkins and Catherine Borger3, Department of Agriculture, 3WAHRI, The University ofWestern Australia 16. Competitiveness of different lupin cultivars with wild radish, Dr Shahab Pathan, Dr Bob French and Dr Abul Hashem, Department of Agriculture 17. Managing herbicide resistant weeds through farming systems, Kari-Lee Falconer, Martin Harries and Chris Matthews, Department of Agriculture 18. Lupins tolerate in-row herbicides well, Peter Newman and Martin Harries, Department of Agriculture 19. Summer weeds can reduce wheat grain yield and protein, Dr Abul Hashem1, Dr Shahab Pathan1 and Vikki Osten3, 1Department Agriculture, 3Senior Agronomist, CRC for Australian Weed Management, Queensland Department of Primary Industries and Fisheries 20. Diuron post-emergent in lupins, the full story, Peter Newman and Glenn Adam, Department of Agriculture 21. Double incorporation of trifluralin, Peter Newman and Glenn Adam, Department of Agriculture 22. Herbicide tolerance of narrow leafed and yellow lupins, Harmohinder Dhammu, David Nicholson, Department of Agriculture 23. MIG narrow leaf lupin herbicide tolerance trial, Richard Quinlan, Planfarm Pty Ltd, Trials Coordinator MIG; Debbie Allen, Research Agronomist – MIG 24. Herbicide tolerance of new albus lupins, Harmohinder Dhammu, David Nicholson, Department of Agriculture 25. Field pea x herbicide tolerance, Mark Seymour and Harmohinder Dhammu, Research Officers, and Pam Burgess, Department of Agriculture 26. Faba bean variety x herbicide tolerance, Mark Seymour and Harmohinder Dhammu, Research Officers, and Pam Burgess, Department of Agriculture 27. Herbicide tolerance of new Kabili chickpeas, Harmohinder Dhammu, Owen Coppen and Chris Roberts, Department of Agriculture 28. Timing of phenoxys application in EAG Eagle Rock, Harmohinder Dhammu, David Nicholson, Department of Agriculture 29. Herbicide tolerance of new wheat varieties, Harmohinder Dhammu, David Nicholson, Department of Agriculture 30. Lathyrus sativus x herbicide tolerance, Mark Seymour, Department of Agriculture 31. Tolerance of annual pasture species to herbicides and mixtures containing diuron, Christiaan Valentine and David Ferris, Department of Agriculture 32. The impact of herbicides on pasture legume species – a summary of scientific trial results across 8 years, Christiaan Valentine and David Ferris, Department of Agriculture 33. The impact of spraytopping on pasture legume seed set, Christiaan Valentine and David Ferris, Department of Agriculture 34. Ascochyta interaction with Broadstrike in chickpeas, H.S. Dhammu1, A.K. Basandrai2,3, W.J. MacLeod1, 3 and C. Roberts1, 1Department of Agriculture, 2CSKHPAU, Dhaulakuan, Sirmour (HP), India and 3CLIMA 35. Best management practices for atrazine in broadacre crops, John Moore, Department of Agriculture, Neil Rothnie, Chemistry Centre of WA, Russell Speed, Department of Agriculture, John Simons, Department of Agriculture, and Ted Spadek, Chemistry Centre of WA 36. Biology and management of red dodder (Cuscuta planiflolia) – a new threat to the grains industry, Abul Hashem, Daya Patabendige and Chris Roberts, Department Agriculture 37. Help the wizard stop the green invaders! Michael Renton, Sally Peltzer and Art Diggle, Department of Agricultur