Phenoloxidase activity and organic carbon dynamics in historic Anthrosols in Scotland, UK.

Phenolic compounds are chemical precursor building blocks of soil organic matter. Their occurrence can be inhibitory to certain enzymes present in soil, thereby influencing the rate of decomposition of soil organic matter. Microbe-derived phenoloxidases (laccases) are extracellular enzymes capable of degrading recalcitrant polyphenolic compounds. In this study, our aim was to investigate the relationships between phenoloxidase enzyme activity, organic carbon content and microbial abundance in the context of long-term anthropogenically amended soils. To achieve this, we used a series of complementary biochemical analytical methods including gas chromatography, enzyme assays and solid-state Carbon-13 Cross Polarisation Magic-Angle Spinning Nuclear Magnetic Resonance Spectroscopy (13C CPMAS NMR). Using several anthrosols found in St Andrews (Scotland, UK) that had been subjected to intense anthropogenic modification since the medieval period (11th century AD) to present-day, we were able to scope the impact of past waste disposal on soils. The long-term anthropogenic impact led to organic matter-rich soils. Overall, phenoloxidase activity increased by up to 2-fold with soil depth (up to 100 cm) and was inversely correlated with microbial biomass. Solid-state 13C NMR characterisation of carbon species revealed that the observed decline in soil organic matter with depth corresponded to decreases in the labile organic carbon fractions as evidenced by changes in the O/N-alkyl C region of the spectra. The increase in phenoloxidase activity with depth would appear to be a compensatory mechanism for the reduced quantities of organic carbon and lower overall nutrient environment in subsoils. By enzymatically targeting phenolic compounds, microbes can better utilise recalcitrant carbon when other labile soil carbon sources become limited, thereby maintaining metabolic processes.

The Past Ubiquity and Environment of the Lost Earth Buildings of Scotland.

This paper investigates the once ubiquitous vernacular earth-built structures of Scotland and how perceptions of such buildings were shaped and developed through periods of intense cultural and environmental change. We focus upon the past exploitation of traditional resources to construct vernacular architectures and on changes in the perception of the resultant buildings. Historic earth-built structures are today deeply hidden within the landscapes of Scotland, although they were once a common feature of both urban and rural settlements. Whilst the eighteenth and nineteenth century period of Improvement - during which many of these structures were destroyed, repurposed, or left to decay - has received extensive attention by historians, there exists no previous serious study of the human and environmental dimensions. Through analysis of the material aspects of landscape resource use and analysis of the historical perceptions of such use, we emphasize the national significance of this undervalued aspect of Scotland's built and cultural heritage, increasingly at risk of being lost completely, highlighting the prior ubiquity of mudwall structures.

Characterising the morphological properties and surface composition of radium contaminated particles: a means of interpreting origin and deposition.

Radioactive 'hot particles' that occur in the environment present specific challenges for health and environmental regulators as often their small size makes them difficult to detect, and they are easily dispersed and accidentally ingested or inhaled by members of the public. This study of nine hot particles recovered from the beach at Dalgety Bay, UK, uses a combination of gamma spectrometry, imaging microscopy and SEM-EDX in order to characterise their morphology and surface composition, thereby helping to identify their origin and source characteristics. The nine particles analysed showed great heterogeneity in their activities, physical form and elemental composition. The particle activities were dominated by (226)Ra and its daughters. Three distinct grouping of particles were identified based on their morphology (artefact, glassy and 'metal-rich'), whilst four distinct groupings (artefact, glassy, angular and porphyric, rounded and highly porous) were identified based on morphology and surface properties as seen in the SEM. Whilst the 'artefact' particles were little altered, the other particles showed evidence of incineration. All particles were in a size and/or shape class vulnerable to wind- or water-mediated transport. No correlations were found between morphology and chemical composition. SEM-EDX analysis revealed C, Si, Zn, Fe, Ca are common in the particles together with Ba, Ni, Pb, Cu, Mn and Ti. This is interpreted as the particles being derived from radium containing luminescent paint containing a Zn/S phosphor, a hydrocarbon base and other fillers and additives. Evidence of copper and steel alloys were also present in some particles, whilst one consisted of a hydrocarbon based 'capsule'. The combination of techniques employed here has enabled interpretation of the origins of the radioactive particles and given insights into the potential movement of particles within the local environment.