Technical note: in situ measurement of flux and isotopic composition of CO2 released during oxidative weathering of sedimentary rocks

Oxidative weathering of sedimentary rocks can release carbon dioxide (CO2) to the atmosphere and is an important natural CO2 emission. Two mechanisms operate – the oxidation of sedimentary organic matter and the dissolution of carbonate minerals by sulfuric acid. It has proved difficult to directly measure the rates at which CO2 is emitted in response to these weathering processes in the field, with previous work generally using methods which track the dissolved products of these reactions in rivers. Here we design a chamber method to measure CO2 production during the oxidative weathering of shale bedrock, which can be applied in erosive environments where rocks are exposed frequently to the atmosphere. The chamber is drilled directly into the rock face and has a high surface-area-to-volume ratio which benefits measurement of CO2 fluxes. It is a relatively low-cost method and provides a long-lived chamber (several months or more). To partition the measured CO2 fluxes and the source of CO2, we use zeolite molecular sieves to trap CO2 actively (over several hours) or passively (over a period of months). The approaches produce comparable results, with the trapped CO2 having a radiocarbon activity (fraction modern, Fm) ranging from Fm = 0.05 to Fm = 0.06 and demonstrating relatively little contamination from local atmospheric CO2 (Fm = 1.01). We use stable carbon isotopes of the trapped CO2 to partition between an organic and inorganic carbon source. The measured fluxes of rock-derived organic matter oxidation (171±5mgCm−2day−1) and carbonate dissolution by sulfuric acid (534±16mgCm−2day−1) from a single chamber were high when compared to the annual flux estimates derived from using dissolved river chemistry in rivers around the world. The high oxidative weathering fluxes are consistent with the high erosion rate of the study region. We propose that our in situ method has the potential to be more widely deployed to directly measure CO2 fluxes during the oxidative weathering of sedimentary rocks, allowing for the spatial and temporal variability in these fluxes to be determined

School dropout, problem behaviour and poor academic achievement : a longitudinal view of portuguese male offenders

This study examines school drop outs from the perspective of male adults themselves through interviews with offenders currently serving sentences. Participants were 10 Portuguese male inmates, between the ages of 19 and 46 years of age, incarcerated in two prison facilities of the Azores. Qualitative and interpretative methods were carried out using a semi-structured in-depth individual interview that was audiorecorded and conducted on the basis of a list of topics. Interview transcripts and thematic analysis were used in data treatment and analysis. The findings primarily indicate that poor academic achievement and emotional and behavioural difficulties of participants played a particular role in early school drop out. The trajectories these individuals followed within the education system presented problem behaviour, learning disabilities, and/or foster care interventions. While school drop out circumstances were apparently various, analysis showed that they were underpinned by three distinct sets of conditions generally not addressed by the education system. The analysis of the triggering factors and the maintenance dynamics of school drop outs indicated three distinct types: retention/absenteeism, life turning points and positive resolution. Implications for secondary prevention and screening practices are discussed.FCT (SFRH/ BD/ 44245/ 2008)CIEC - unidade de investigação 317 da FC

Investigating Carbon Dioxide Emissions from Oxidative Weathering of Sedimentary Organic Matter

No abstract available

Drug testing and court review hearings: uses and limitations

The ability of the UK criminal justice system to divert drug-dependent offenders into treatment has been enhanced during recent years. Despite the rapid expansion of such coercive measures, research findings to date are equivocal about their impact. This article draws on qualitative data from in-depth interviews with professionals and those mandated to treatment by the courts to assess the uses and limitations of two defining features of court-ordered drug treatment in Britain and elsewhere – drug testing and court review hearings – as a means of promoting and monitoring compliance with the conditions of these disposals

ALICE upgrades during the LHC Long Shutdown 2

International audienceA Large Ion Collider Experiment (ALICE) has been conceived and constructed as a heavy-ion experiment at the LHC. During LHC Runs 1 and 2, it has produced a wide range of physics results using all collision systems available at the LHC. In order to best exploit new physics opportunities opening up with the upgraded LHC and new detector technologies, the experiment has undergone a major upgrade during the LHC Long Shutdown 2 (2019–2022). This comprises the move to continuous readout, the complete overhaul of core detectors, as well as a new online event processing farm with a redesigned online-offline software framework. These improvements will allow to record Pb-Pb collisions at rates up to 50 kHz, while ensuring sensitivity for signals without a triggerable signature