Measuring Ozone Deposition to the Ocean Surface and Assessing its Biogeochemical Controls

Dry deposition of ozone to the sea surface represents a significant portion of global tropospheric ozone loss. It introduces considerable uncertainty in global models due to limited understanding of the reactivity of iodide and organic material in the sea surface towards ozone. This is particularly true of organic material due to its variable composition. This thesis details ozone flux and associated measurements at and around the Penlee Point Atmospheric Observatory (PPAO) on the UK south coast from 2018 until 2021 where coastal ozone flux was calculated via eddy covariance. Monthly median deposition velocity was 0.007 – 0.033 cm s−1 across all fieldwork, similar to the values reported from ship-based measurements: 0.009 – 0.034 cm s−1. Iodide and dissolved organic carbon (DOC) concentrations in the water within the flux footprint were ~50 to ~100 nmol dm−3 and 1.3 – 2.2 mg dm−3. While iodide increased to a peak in July (coinciding with phytoplankton blooms), DOC conversely peaked in November. These measurements were used with a 1-layer and a 2-layer model to compare deposition observations to predictions. The 1-layer model in the absence of DOC reactivity typically gave values closest to observations and showed a similarly strong variation with friction velocity. Inclusion of the DOC-ozone reaction with a rate constant of 3.7 × 10−6 dm3 mol−1 s−1 caused both models to overestimate, but also mimic some variation between months suggesting its contribution was overestimated, but still important. Liquid chromatography-mass spectrometry was used to identify compounds in the water near the PPAO. Double bond equivalence decreased following exposure to 500 ppbv ozone, while dicarboxylic acid concentrations increased, potentially due to unsaturated fatty acid ozonolysis. Several dicarboxylic acid concentrations in PPAO samples fell from November – April, similarly to DOC concentrations. The potential for some introduction of dicarboxylic acids as contaminants from the sampling method remains a possibility

Martyrologists without boundaries: the collaboration of John Foxe and Heinrich Pantaleon

Amid the great Protestant martyrologies of the mid-sixteenth century, Heinrich Pantaleon’s Martyrvm historia (1563) has been comparatively overlooked. This article argues that Pantaleon’s martyrology acted as a capstone to the narrative framework of Protestant suffering and resistance. Pantaleon’s command of vernacular languages gave him access to a wider range of material than other martyrologists, material which his Latin text made accessible to learned readers across Europe. This article also examines the collaboration between Pantaleon and John Foxe, which directly inspired Pantaleon’s martyrology and enabled Foxe to give a cohesive, trans-European account of Protestant martyrs in his Acts and monuments

Root age influences failure location in grass species during mechanical testing

Aims: Root tensile tests are often rejected if failure location is outside the middle section of samples. This study aims to identify where and why failure occurs along a root axis, and hence to revisit current approaches to test-validity.Methods: Roots from Festuca arundinacea; Lolium multiflorum; Lolium perenne were sampled from field-grown plants. Roots were tensile tested using a universal testing machine. Root samples were randomly allocated into two groups for testing. Group 1 roots were orientated with the older tissue closest to the top clamp, group 2 roots were orientated oppositely. Tensile strength, Young’s modulus and failure location were recorded for each sample.Results: Lolium multiflorum roots were thinner and stronger than roots of Festuca arundinacea. Failure location in tensile tests depended significantly on tissue age with 75% of samples failing in the younger third of root tissue regardless of the root orientation in the testing frame. Only 7% of roots failed in the middle third of the sample.Conclusions: Fibrous roots tested in tension were observed to consistently fail in the younger tissue along the root axis. Exclusion of samples which fail outside the middle region of the root axis needs re-evaluation for a range of species

Do adolescents with Chronic Fatigue Syndrome (CFS/ME) and co-morbid anxiety and/or depressive symptoms think differently to those who do not have co-morbid psychopathology?

Background: Co-morbid anxiety and/or depression is common in adolescents with Chronic Fatigue Syndrome (CFS/ME). Adolescents with psychopathology typically endorse more negative cognitive errors. We don’t know whether they make negative cognitive errors in response to fatigue. We examined the thinking patterns of adolescents with CFS/ME and co-morbid psychopathology compared to those without this co-morbidity. Methods: This cross-sectional study recruited 205 adolescents (age 11-18) with CFS/ME, who completed measures of anxiety and depression, information processing biases and responses to fatigue. We grouped participants as having co-morbid psychopathology (or not) by applying a threshold score. We compared groups’ thinking pattern subscale scores using independent samples T tests. We examined the association between psychopathology and general negative thinking and specific responses to fatigue symptoms. Results: Adolescents with CFS/ME with co-morbid psychopathology more strongly endorsed general negative cognitive errors (d = 0.61-1.31). They also more strongly endorsed damage beliefs (d = 0.49), embarrassment avoidance (d = 1.05), catastrophising (d = 0.97) and symptom focusing (d = 0.75) in response to fatigue but did not differ significantly on fear avoidance from those without co-morbid psychopathology. Both negative cognitive errors and unhelpful responses to symptoms explained 43% of the variance in psychopathology. Conclusions: Adolescents with CFS/ME with co-morbid psychopathology tend to be negatively biased in their thinking, both generally and about their symptoms of fatigue specifically. This may have implications for the sequencing of cognitive and behavioural strategies to address both fatigue and psychopathology. <br/

Realistic scaling of plant root systems for centrifuge modelling of root-reinforced slopes

Vegetation as a means to improve slope stability is well recognised and incorporated in geotechnical and ecological engineering practice to protect slopes against shallow landslides. Much of the research in this area has quantified root reinforcement of soil shear behaviour at prescribed soil depths in either the laboratory or the field. Costs and practicality limit testing of global behaviour, where full-scale field trials can be brought to failure to determine plant root impacts on the depth of failure and critical hydrological conditions. Geotechnical centrifuge modelling offers an opportunity to investigate in detail the engineering performance of vegetated slopes, but its application has been restricted due to the challenge of scaling plant root systems. Some work has relied on scaled model roots, provided by either live plants or analogue material with similar mechanical properties (stiffness and strength) and a realistic 3-D geometry at small scale.For root analogues, a 3-D printing technique has recently been introduced by the authors, to reproduce representative root morphologies with appropriate mechanical properties (Liang et al., 2015). This 3-D printing technique has been used in centrifuge tests of sandy slopes subject to earthquake loadings, and showed substantial benefits of analogue root reinforcement.In previous studies using live plants (e.g. Sonnenberg et al., 2010), model scaling effects have not been considered in detail. This may have contributed to over-prediction of root reinforcement and relatively poor prediction of slope response. We are performing studies to identify candidate species to better represent scaled root morphologies and mechanical characteristics for use in centrifuge modelling. Three species (willow, gorse and grass), corresponding to distinct plant groups were selected and cultivated for approximately two months following preliminary assessment of suitable species. Root morphologies, tensile strengths and Young’s modulus of these juvenile root samples were then measured and compared with results from more mature field grown specimens. Results from these tests will be discussed in relation to the use of juvenile plant root systems and root system analogues in scaled centrifuge testing