Influence of nitrogen deposition on carbon dynamics in peatlands

The impact of high levels of nitrogen deposition from the atmosphere (primarily from the combustion of fossil fuels and transportation) on soil carbon fluxes and carbon sequestration pathways in peatlands are uncertain and limit our understanding of its consequence on peatlands’ role as global carbon sinks. An alteration in peatlands’ natural carbon accumulation process could result in the increased release of CO2 into the atmosphere, potentially increasing the greenhouse effect and contributing to climate change. Recent studies in forest soils have shown that high concentrations of inorganic nitrogen accelerate the activity of key soil enzymes involved in the degradation of easily decomposable litter (low lignin content) but slow down the decomposition of lignin abundant litter. Peatland soils are adapted to slow rates of nitrogen mineralization; therefore increasing the nitrogen supply in these environments may have an even deeper impact on litter quality, potential litter decomposability, and overall carbon storage capacity. The aim of this study is to use plant wax biomarkers as proxies of vegetational change in litter profiles. An alkane and alcohol profile database of peatland vegetation is currently being characterized for comparison with samples taken from the Whim Moss experimental site (Edinburgh) where different levels of nitrogen has been added to peatland soil since 2002. A temporal study combining the MicroResp technique (community level physiological profiles) and enzyme activity assays is considered to look at the effect of litter compositional changes on soil microbial diversity and biological activity. To better understand how nitrogen deposition in peatland soil affects the mechanisms controlling carbon storage, the incorporation of stable isotope labelling (13C) would allow direct determination of the fate of carbon into the different carbon pools and better pin-point the changes in litter composition

Root traits predict decomposition across a landscape-scale grazing experiment

Acknowledgements We are grateful to the Woodland Trust for maintenance of and access to the Glen Finglas experiment. We thank Debbie Fielding, William Smith, Sarah McCormack, Allan Sim, Marcel Junker and Elaine Runge for help in the field and the laboratory. This research was part of the Glen Finglas project (formerly Grazing and Upland Birds (GRUB)) funded by the Scottish Government (RERAS). S.W.S. was funded by a BBSRC studentship.Peer reviewedPublisher PD

Combination of herbivore removal and nitrogen deposition increases upland carbon storage

© 2015 The Authors. Global Change Biology Published by John Wiley & Sons Ltd. Acknowledgements We thank Ruth Mitchell, Alison Hester, Bob Mardon, Eoghain Maclean, David Welch, National Trust for Scotland, Scottish Natural Heritage and the Woodland Trust for helping find appropriate exclosures and granting access permission. We thank Nick Littlewood and Antonio Lopez Nogueira for their assistance in the field and processing samples in the lab and Ron Smith and Tony Dore for providing N deposition data. SWS was funded by a BBSRC studentship.Non peer reviewedPublisher PD

Asymmetry and decoherence in a double-layer persistent-current qubit

Superconducting circuits fabricated using the widely used shadow evaporation technique can contain unintended junctions which change their quantum dynamics. We discuss a superconducting flux qubit design that exploits the symmetries of a circuit to protect the qubit from unwanted coupling to the noisy environment, in which the unintended junctions can spoil the quantum coherence. We present a theoretical model based on a recently developed circuit theory for superconducting qubits and calculate relaxation and decoherence times that can be compared with existing experiments. Furthermore, the coupling of the qubit to a circuit resonance (plasmon mode) is explained in terms of the asymmetry of the circuit. Finally, possibilities for prolonging the relaxation and decoherence times of the studied superconducting qubit are proposed on the basis of the obtained results.Comment: v.2: published version; 8 pages, 12 figures; added comparison with experiment, improved discussion of T_ph

Milling plant and soil material in plastic tubes over-estimates carbon and under-estimates nitrogen concentrations

Peer reviewedPostprin

Low-light-level nonlinear optics with slow light

Electromagnetically induced transparency in an optically thick, cold medium creates a unique system where pulse-propagation velocities may be orders of magnitude less than $c$ and optical nonlinearities become exceedingly large. As a result, nonlinear processes may be efficient at low-light levels. Using an atomic system with three, independent channels, we demonstrate a quantum interference switch where a laser pulse with an energy density of $\sim23$ photons per $\lambda^2/(2\pi)$ causes a 1/e absorption of a second pulse.Comment: to be published in PR

Movement from the double object construction is not fully symmetrical

A movement asymmetry arises in some languages that are otherwise symmetrical for both A- and A-bar movement in the double object construction (DOC), including Norwegian, North-West British English, and a range of Bantu languages including Zulu and Lubukusu: a Theme object can be A-bar-moved out of a Recipient (Goal) passive, but not vice versa. Our explanation of this asymmetry is based on phase theory, more specifically a stricter version of the Phase Interpretability Condition proposed by Chomsky (2001). The effect is that, in a Theme passive, a Recipient object destined for the C-domain gets trapped within the lower V-related phase by movement of the Theme. The same effect is observed in Italian, a language in which only Theme passives are possible. Moreover, a similar effect is also found in some Bantu languages in connection with object marking/agreement: object agreement with the Theme in a Recipient passive is possible, but not vice versa. We show that this, too, can be understood within the theory that we articulate

From citizen science to citizen action: analysing the potential for a digital platform to cultivate attachments to nature

Identifying private gardens in the UK as key sites of environmental engagement, we look at how a longer-term online citizen science programme facilitated the development of new and personal understandings of nature. These were visible through new or renewed interest in wildlife-friendly gardening practices and attitudinal shifts in a large proportion of its participants. Qualitative and quantitative data, collected via interviews, focus groups, surveys and logging of user behaviours, revealed that cultivating a fascination with species identification was key to both ‘helping nature’ and wider learning, with the programme creating a space where scientific and non-scientific knowledge could co-exist and reinforce one another

The abiotic removal of organic micropollutants with iron and manganese oxides in rapid sand filters for groundwater treatment

Rapid sand filters (RSFs) have shown potential for removing organic micropollutants (OMPs) from groundwater. However, the abiotic removal mechanisms are not well understood. In this study, we collect sand from two field RSFs that are operated in series. The sand from the primary filter abiotically removes 87.5% of salicylic acid, 81.4% of paracetamol, and 80.2% of benzotriazole, while the sand from the secondary filter only removes paracetamol (84.6%). The field collected sand is coated by a blend of iron oxides (FeOx) and manganese oxides (MnOx) combined with organic matter, phosphate, and calcium. FeOx adsorbs salicylic acid via bonding of carboxyl group with FeOx. The desorption of salicylic acid from field sand indicates that salicylic acid is not oxidized by FeOx. MnOx adsorbs paracetamol through electrostatic interactions, and further transforms it into p-benzoquinone imine through hydrolysis-oxidation. FeOx significantly adsorbs organic matter, calcium, and phosphate, which in turn influences OMP removal. Organic matter on field sand surfaces limits OMP removal by blocking sorption sites on the oxides. However, calcium and phosphate on field sand support benzotriazole removal via surface complexation and hydrogen bonding. This paper provides further insight into the abiotic removal mechanisms of OMPs in field RSFs

A Role for the Autonomic Nervous System in Modulating the Immune Response during Mild Emotional Stimuli

The role of the autonomic nervous system in the modulation of the immune response to emotional stimuli, was established in rats subjected to the passive avoidance test. An increase in splenic primary antibody response directed against SRBC was found after exposure of rats to the passive avoidance apparatus (novelty). Both local surgical denervation of the spleen and β-receptor blockade (timolol, 1 mg/kg i.p. 1 h prior to testing) prevented the increase in primary antibody response