The Impact Of Living Walls In The Reduction Of Atmospheric Particulate Matter Pollution

Traffic-generated particulate matter (PM) air pollution remains a serious threat to human health and the environment. Whilst the ability of vegetation to reduce PM pollution is widely recognised, little or no information is available on the value of living walls in this respect. This thesis explored their potential to serve as near-road/rail PM filters, and evaluated the optimal conditions required to maximise their PM capture efficiency, using both field and laboratory-based techniques. This study revealed living walls could immobilise substantial levels of PM associated with both road and rail traffic. Of three living walls studied, one, located along a busy road, was shown to remove substantial levels of PM1 (122.08 ± 6.9 x 107) and PM10 (4.45 ± 0.33 x 107) per 100 cm2; the highest level of PM2.5 removal (9.9 ± 5 x 107) was recorded from a wall located near a busy train station. The best PM-removing species, and the important leaf traits, were identified using living wall plants and natural/synthetic leaf models. There was a considerable inter-species variation in PM accumulation and the PM densities on some species were x50 and x65 higher compared to others. The influence of leaf size on PM accumulation was found to be dominant over other examined characters (leaf size, shape, and micromorphology); smaller leaved species with a high Leaf Area Index were identified as the most efficacious. Analysis of captured PM from rail and road traffic showed the ability of living wall plants to immobilise a wide range of elements which are known to be hazardous to health. Simulated rainfall demonstrated the potential for rain to wash particulates off leaves and renew capture surfaces to ensure their continuous functioning; wash-off removed between 48.4% and 92.5% of particles depending on the species. An impact of planting design on the PM reduction performance of living wall species was demonstrated by the superior capture efficiency resulting from increasing the topographical heterogeneity of plantings. This research enhances our understanding of the benefits of living wall systems in relation to PM pollution mitigation, and consequent improvement of human wellbeing

Mitigation of drought damage to rapeseed (Brassica napus L.) from sprays of film antitranspirants at different concentrations.

Drought causes massive yield losses in rapeseed (Brassica napus), particularly during flowering when crops are most sensitive to water stress. It has been shown that film antitranspirant (AT) can effectively improve the yield of droughted rapeseed if applied at the flowering stage, yet the mechanism by which film AT mitigates drought damage and the concentration-response relationship between AT and crop yield remain unclear. To understand the underlying physiological mechanism and determine the optimum concentration of AT for rapeseed, the following experiments were conducted: five experiments measuring leaf coverage; three experiments imposing a short-term controlled drought during the flowering stage in the glasshouse; two experiments imposing a terminal drought in the field under polytunnels. Results showed that AT application at the early flowering stage decreased stomatal conductance more than photosynthesis of rapeseed, which improved intrinsic water use efficiency under both drought conditions. This suppression of gas exchange was positively correlated with AT concentrations due to changes in leaf coverage. However, yield responses to AT were only observed when rapeseed was under terminal drought, with increasing AT concentrations resulting in higher yields. Across concentrations and two sites, AT increased seed yield by 24%, predominantly from pod number increases compared to droughted control. Rapeseed treated with 3% AT produced the highest seed yield by 37% over unsprayed droughted plots, with about 31% adaxial leaf coverage. Pod number and leaf relative water content were positively correlated. It was concluded that yield benefits from AT application might be mediated by improving leaf water status to sustain rapeseed pod formation, and a greater yield can be achieved by increasing AT concentrations with conventional spraying on the adaxial surface. Therefore, the interactive effects of drought with AT concentrations and developing a cost effective spraying method by also covering the abaxial leaf surface would merit further investigation

Application of proximal sensing techniques for epidemiological investigations of <em>Fusarium </em>head blight in wheat under field and controlled conditions

Sensors can provide valuable insight into studying the physiological disorder due to plant pathogens. Fusarium head blight (FHB) influences the optical properties of wheat (Triticum aestivum L.) at canopy and ear levels. This research aimed to investigate these complex disease situations under field as well as controlled conditions with the application of proximal sensing systems. Observations under field conditions revealed that the presence of foliar diseases is associated with higher Fusarium infection in the wheat canopy (cv. Tobak and Pamier), which might be attributed to reduced defence mechanisms. This was reflected in increased FHB incidence visually assessed at growth stage (GS) 83. Fungicides applied against foliar diseases before anthesis reduced FHB presence, which might be not only due to reducing the available inoculum in the canopy but also due to promoting defenses against Fusarium infection. Furthermore, prediction of FHB through spectral parameters such as blue-green index 2 (BGI2) and photochemical reflection index (PRI) proved to be very promising. At ear level, development of Fusarium infection is dependent on the primary infection site within ears and the prevailing environmental conditions after infection. Such a relationship was verified under controlled conditions after tip, centre and base inoculations, separately, by F. graminearum and F. culmorum of wheat ears (cv. Passat). Symptom dynamics (FHB index) were slower downwards within ears in comparison to the upward development. In contrast to the symptom appearance the infection of Fusarium species proved to be directed basipetally – a rare development of fungal infections. According to these observations it could be revealed that higher temperatures accelerated the ripening of ears and allowed these plants to escape the infection within ears. In contrast, at lower temperatures, higher disease severity was observed even for tip infection. Infrared thermography could predict this primary site of ear infection through temperature span within ears and enabled disease detection before symptoms became visible. The temperature difference between air and ear was negatively correlated to FHB index and allowed disease detection at early senescence stage. Combining the features of thermal measurements and chlorophyll fluorescence images proved to present a high potential in characterising FHB at spikelet level. Discriminating spikelets infected with F. graminearum from those infected with F. culmorum were enabled up to 100% accuracy by fusion of sensor data. This study demonstrated that FHB is influenced by foliar wheat diseases when at low severities of both. The control of leaf pathogens by fungicides can play an important part in integrated disease management – also against Fusarium infections. It could also be confirmed that primary infection sites within ears and the prevailing environmental conditions after infection are key factors which determine the later development of FHB. Sensors proved to be useful in monitoring and assessing FHB under field conditions – detailed investigations under controlled conditions provided more profound insights in this regard. The findings of this research contribute to more efficient control of FHB using the concepts of remote sensing to improve precision plant protection and may be applied in selection processes of breeding for FHB resistance as well.Geeignete Sensoren können einen wertvollen Einblick in die physiologischen Verhältnisse in Pflanzen bieten, wenn diese von pathogenen Organismen heimgesucht werden. Die Infektionen von Getreide durch Fusarium Arten (Fusarium Head Blight = FHB) verändern die optischen Eigenschaften von Wirtspflanzen – vor allem von Weizen (Triticum aestivum L.) – sowohl im Getreidestand als auch auf dem Niveau der einzelnen Ähren. Die vorliegenden Untersuchungen hatten zum Ziel, die näheren Gegebenheiten dieser komplexen Befallssituationen im Freiland und unter kontrollierten Bedingungen durch die Anwendung von zerstörungsfreien Messmethoden zu charakterisieren. Erhebungen im Feld machten deutlich, dass der Befall mit Fusarium Arten durch das Auftreten weiterer Blattkrankheiten im Weizenbestand gefördert wurde. Dies wurde beispielhaft an den Sorten „Tobak“ und „Pamier“ ermittelt und deutet auf eine geringere Widerstandsfähigkeit der Pflanzen gegenüber Fusariosen bei multiplem Befall hin. Dies konnte im Wachstumsstadium 83 (BBCH-Skala) auch makroskopisch festgestellt werden. Fungizidanwendungen, die vor der Blüte durchgeführt wurden, konnten das Auftreten der Fusarien am Weizen reduzieren. Dies war zweifellos auf die Reduktion des verfügbaren Inokulums der Fusarium-Arten zurückzuführen. Zugleich kann angenommen werden, dass durch die Gesunderhaltung der Blattfläche auch eine erhöhte Widerstandsfähigkeit der Pflanzen gegenüber Fusariosen hervorgerufen werden. Die Möglichkeit zur Vorhersage von FHB durch spektrale Parameter konnte bestätigt werden – vor allem an Hand des Blue- Green-Index 2 (BGI2) und des photochemischen Reflektionsindexes (PRI) erwiesen sich als besonders geeignet. An der Getreideähre ist die Entwicklung der Fusariosen in hohem Maße abhängig von dem primären Infektionsort und den nachfolgenden Umweltbedingungen im Anschluss an die Primärinfektion der Ähre. Dies konnte unter kontrollierten Bedingungen am Weizen der anfälligeren Sorte „Passat“ für Primärinokulationen an der an der Spitze, in der Mitte und an der Basis der Ähren nachgewiesen werden. Es zeigte sich, dass die Symptomentwicklung (FHB index) in der Ähre deutlich weniger nach unten gerichtet war, als in der Zone oberhalb des Inokulationspunktes. Dies galt sowohl für Infektionen durch F. graminearum als auch für F. culmorum. Im Gegensatz zur Symptomentwicklung entwickeln sich die Fusariosen vor allem abwärts in der Ähre – ein durchaus eher seltener Prozess für pflanzenpathogene Organismen. Erhöhte Temperaturen beschleunigen die Reifung der Ähren – obwohl günstig für das Auftreten von Fusariosen ermöglichen diese Bedingungen auch ein „disease escape“ gegenüber Fusarium-Arten. Bei niedrigeren Temperaturen führen die Infektionen zu deutlich höheren Infektionsraten, weil mehr Zeit zur Ausbreitung besteht – selbt in den Ährenspitzen. Mit Hilfe der Infrarot-Thermographie gelang es, die Primärinfektionen in der Ähre durch die Temperaturdifferenz zwischen Umwelt und den biologisch relevanten Zonen zu charakterisieren bevor bereits makroskopisch Symptome erkennbar wurden. Die Gewebetemperaturdifferenzen waren negativ korreliert mit dem FHB index – sie erlaubten aber auch eine Bestimmung des Reifestatus der Ähren. Wurden die Infrarotmessungen mit der Messung von Chlorophyllkorrelierten Messungen zerstörungsfrei kombiniert, lies sich damit eine hohe Korrelation identifizieren – insbesondere auf dem Niveau der einzelnen Ährchen. Wurden diese Beziehungen betrachtet, dann zeigte sich, dass sich sogar Unterschiede zwischen F. graminearum und F. culmorum erkennen ließen. Die vorliegenden Untersuchungen zeigen, dass das Auftreten von Fusariosen an Getreide auch in besonderem Umfang durch andere Blattkrankheiten gefördert wird – erkennbar allerdings nur bei geringen Befallsintensitäten. Die Förderung der Pflanzengesundheit – auch durch Fungizide – kann zu einer wichtigen Funktion im Integrierten Pflanzenschutz führen – sicher auch zum Schutz vor Ährenfusariosen. Es konnte nachgewiesen und durch Anwendung geeigneter Sensoren genutzt werden, dass die Fusarium-Infektionen eine besondere Rolle spielen. Vor allem die Primärinfektionsorte, die sehr umweltabhängig sind – haben großen Einfluss auf die Schadwirkung. Sensoren können offenbar sehr hilfreich bei dem Erkennen und der Befallsbestimmung – und das bereits unter Freilandbedingungen. Dies wurde durch Erhebungen unter Feldbedingungen bestätigt – ergänzt durch weitere Untersuchungen unter praktischen Bedingungen. Die vorliegenden Ergebnisse und Erkenntnisse können eine effizientere Unterdrückung von FHB ermöglichen. Dabei geht es darum, dass die Elemente des „sensing of diseases“ einerseits in den Integrierten Pflanzenschutz eingebunden werden können und zudem auch für Selektionsprozesse in der Züchtung zur Vermeidung von FHB genutzt werden kann

Geoengineering the climate: science, governance and uncertainty

Geoengineering, or the deliberate large-scale manipulation of the planetary environment to counteract anthropogenic climate change, has been suggested as a new potential tool for addressing climate change. Efforts to address climate change have primarily focused on mitigation, the reduction of greenhouse gas emissions, and more recently on addressing the impacts of climate change—adaptation. However, international political consensus on the need to reduce emissions has been very slow in coming, and there is as yet no agreement on the emissions reductions needed beyond 2012. As a result global emissions have continued to increase by about 3% per year (Raupach et al. 2007), a faster rate than that projected by the Intergovernmental Panel on Climate Change (IPCC) (IPCC 2001)7 even under its most fossil fuel intensive scenario (A1FI8) in which an increase in global mean temperature of about 4°C (2.4 to 6.4°C) by 2100 is projected (Rahmstorf et al. 2007). The scientifi c community is now becoming increasingly concerned that emissions will not be reduced at the rate and magnitude required to keep the increase in global average temperature below 2°C (above pre-industrial levels) by 2100. Concerns with the lack of progress of the political processes have led to increasing interest in geoengineering approaches. This Royal Society report presents an independent scientifi c review of the range of methods proposed with the aim of providing an objective view on whether geoengineering could, and should, play a role in addressing climate change, and under what conditions

Application of multi-scale assessment and modelling of landfill leachate migration: implications for risk-based contaminated land assessment, landfill remediation, and groundwater protection

There are a large number of unlined and historical landfill sites across Britain, contaminating groundwater and soil resources as well as posing a threat to human health and local communities. There is an essential requirement for robust methodology when carrying out risk-based site investigations prior to risk assessment and remediation of landfill sites. This research has focused upon the methods used during site investigations for two reasons. Firstly, the site investigation is often conducted using field instruments and methods that do not account for the heterogeneous conditions found at landfill sites. Interpreting geophysical conditions between sampled points is a common practise. Given the complex and heterogeneous conditions at landfill sites, such methodology introduces uncertainty into data sets. Secondly, risk estimation models that simulate groundwater flow and contaminant transport require extensive field information. The data used during model construction will significantly impact contaminant transport simulations. Modelling guidelines also need further development, ensuring that sound modelling practises are adhered toduring model construction.To address these concerns, four research objectives were identified: (1) Two new multi-spatial field assessment methods (remote sensing and ground penetrating radar), previously applied in other fields of science, were tested on landfill sites; (2) Kriging was used as a tool to improve landfill-sampling strategies; (3 & 4) Groundwater flow and contaminant transport models were used to evaluate whether different scales of field data and modelling practises influenced modelling assumptions and simulation.The utility of novel field- and airborne-based remote sensing methodologies in identifying the location and intensity of vegetation stress caused by leachate migration and inferring pathways of near surface contamination using patterns of vegetation stress was proven. The results from the kriging investigations demonstrated that additional insight into field conditions could be resolved to identify locations of additional sampling points, and provide information about variability in hydrological data sets. The Ground Penetrating Radar investigations provided three types of valuable near-surface information that could assist in determining landfill risks: buried landfill features, leachate plume locations and local hydrogeological conditions. These combined methods provided detailed synoptic geophysical and contaminant information that would otherwise be difficult to determine. Their application and acceptance as site assessment methods (used under certain landfill conditions) could increase the accuracy of assessing risks posed by landfill leachate.These applications also demonstrated that the most effective site assessments are achieved when integrated with other field data such as soil, vegetation, and groundwater quantity measurements, contaminant concentrations and aerial photographs, providing comprehensive information needed for risk estimation modelling.The modelling analyses found that close attention must be paid to site-specific and model-specific characteristics, as well as modelling practises. These factors influenced model results. By using additional data to infer model parameters, it was evident that the amount of data available will influence the way in which risk will be perceived. The more data that was available during model construction, the higher the risk prediction. This was the case for some seventy- percent of the models.By improving the accuracy of site investigation methodology, and by adhering to robust assessment and modelling practices, a higher level of quality assurance can be achieved in the risk assessment and remediation of contaminating landfill sites. If the improvements and recommendations presented in this research are considered, uncertainties inherent in the site investigation could be reduced, therefore enhancing the accuracy of landfill risk assessment and remedial decisions