150 research outputs found
Understanding former heroin users' experience of change: An interpretative phenomenological analysis
This study aimed to explore the experiences of those who have been involved in change from problematic heroin use and how they have made sense out of their experiences.Seven participants, who had been abstinent from heroin for a minimum of two years were interviewed about their experience of change. Practicing drug workers were chosen who had previously used heroin and were now employed to support individuals who were still using drugs. In this way they represented former drug users who had made significant long-term change.Interviews were analysed using Interpretative Phenomenological Analysis (IPA). Three superordinate themes were identified, which were, âMaking sense of changeâ, âIdentity, Relationships and Lifestyleâ and âInternal Distressâ. A number of subthemes were also identified for each superordinate theme.Implications for substance misuse and Counselling Psychology included increasing awareness of the complexity and factors involved in change and appreciating change from former heroin usersâ perspectives. This challenged current and more popularly-held perspectives consistent with political and organisational agendas which focus upon costs associated with heroin use.Factors such as a change of mind-set, identification of avoidance behaviours to manage emotional pain and distress and finding alternative ways of managing pain may also apply to other forms of change, such as other forms of addictions and weight loss.Implications for Counselling Psychology included a consideration of self-transformation and the factors which may initiate behavioural change and the importance of appreciating ongoing aspects of change including identity, relationships and lifestyle
Chemical and isotopic characteristics of weathering and nitrogen release in non-glacial drainage waters on Arctic tundra
Soilâwater interactions in coastal tundra soils are a potential source of nutrients for surrounding fjordal and coastal ecosystems. Changes in water chemistry and stable isotope composition from three streams in west Spitsbergen were examined to assess the sources and losses of nitrogen, sulfur and carbon in thin organic tundra soils overlying sediments. Studies were undertaken from snowmelt (mid June) through to the end of the summer (September) in both 2001 and 2002. Drainage water chemistry was dominated by the solution of CaâMg carbonates with δ13C values in the waters being uncharacteristically high (approx. â2â° at the end of the season), reflecting a largely open system in which the CO2 is derived equally from the atmosphere and plant/soil sources. Early melt waters had δ34S values dominated by sea salt reflecting the close proximity to the ocean. However, as the season progressed the marine influence lessened. Extrapolation of the data suggests that the origin of non-sea salt δ34S was the oxidation of reduced sulfur from coal particles in the subsoil. Concentrations of inorganic N in stream waters were generally very low. However, values were found to increase as the season progressed, possibly through increased microbial activity in the soil and the early senescence of tundra plants reducing demand. Dual isotope analysis of δ15N and δ18O suggested that the vast majority of snow-pack was assimilated by the soil microbial biomass before being released, recycled and lost to drainage waters. Organic N concentrations in drainage waters were generally equal to or greater than losses of inorganic N from tundra soils. The study demonstrated the effectiveness of stable isotope data for understanding biogeochemical cycling and soilâwater interactions in tundra ecosystems. The implications of the results are discussed in relation to climate warming
The sensitivity of cosmogenic radionuclide analysis to soil bulk density: implications for soil formation rates
Improving our knowledge of soil formation is critical so that we can better understand the firstâorder controls on soil thickness and more effectively inform landâmanagement decisions. Cosmogenic radionuclide analysis has allowed soil scientists to more accurately constrain the rates at which soils form from bedrock. In such analysis, the concentration of an isotope, such as Berylliumâ10, is measured from a sample of bedrock. Because this concentration is partly governed by the lowering of the bedrockâsoil interface, a cosmogenic depthâprofile model can be fitted to infer the bedrock and surface lowering rates compatible with the measured concentrations. Given that the bedrockâsoil interface is shielded by soil, the cosmic rays responsible for the inâsitu production of the radionuclide are attenuated, with attenuation rates dependent on the density profile of this soil. Many studies have assumed that soil bulk density is either equal to that of the bedrock or constant with depth. The failure to acknowledge the variations in soil bulk density means that cosmogenically derived soil formation rates previously published may be underâ or overestimates. Here, we deploy a new model called âCoSOILcalâ to a global compilation of cosmogenic analyses of soil formation and, by making use of estimated bulk density profiles, recalculate rates of soil formation to assess the sensitivity to this important parameter. We found that where a soil mantle >0.25âm overlies the soilâbedrock interface, accounting for the soil bulk density profile brings about a significantly slower rate of soil formation than that previously published. Moreover, the impact of using bulk density profiles on cosmogenically derived soil formation rates increases as soil thickens. These findings call into question the accuracy of our existing soil formation knowledge and we suggest that future cosmogenic radionuclide analysis must consider the bulk density profile of the overlying soil
The Sensitivity of Cosmogenic Radionuclide Analysis to Soil Bulk Density:Implications for Soil Formation Rates
Improving our knowledge of soil formation is critical so that we can better understand the first-order controls on soil thickness and more effectively inform land-management decisions. Cosmogenic radionuclide analysis has allowed soil scientists to more accurately constrain the rates at which soils form from bedrock. In such analysis, the concentration of an isotope, such as Beryllium-10, is measured from a sample of bedrock. Because this concentration is partly governed by the lowering of the bedrock-soil interface, a cosmogenic depth-profile model can be fitted to infer the bedrock and surface lowering rates compatible with the measured concentrations. Given that the bedrock-soil interface is shielded by soil, the cosmic rays responsible for the in-situ production of the radionuclide are attenuated, with attenuation rates dependent on the density profile of this soil. Many studies have assumed that soil bulk density is either equal to that of the bedrock or constant with depth. The failure to acknowledge the variations in soil bulk density means that cosmogenically derived soil formation rates previously published may be under- or overestimates. Here, we deploy a new model called "CoSOILcal" to a global compilation of cosmogenic analyses of soil formation and, by making use of estimated bulk density profiles, recalculate rates of soil formation to assess the sensitivity to this important parameter. We found that where a soil mantle >0.25 m overlies the soil-bedrock interface, accounting for the soil bulk density profile brings about a significantly slower rate of soil formation than that previously published. Moreover, the impact of using bulk density profiles on cosmogenically derived soil formation rates increases as soil thickens. These findings call into question the accuracy of our existing soil formation knowledge and we suggest that future cosmogenic radionuclide analysis must consider the bulk density profile of the overlying soil. Highlights The effect of heterogeneities in soil bulk density on cosmogenically derived soil formation rates is unknown. Soil formation rates are recalculated using a new model to analyse the effect of density variations. Accounting for density in soils >0.25 m thickness brings about significantly slower soil formation rates. Measuring soil bulk density is essential when cosmogenically deriving soil formation rates
Carbon sequestration in the soils of Northern Ireland: potential based on mineralogical controls
Complex relationships between soil organic carbon (SOC), mineralogy, land-use and climate may exist in the soils of Northern Ireland. Greater understanding of these interactions can improve the effectiveness of SOC sequestration and management strategies. Mineralogy and SOC concentrations in soils derived from four different parent rocks (sandstone, shale, basalt and granodiorite) were characterised and indicate that soil mineralogy and geochemistry play an important role in determining the concentration of SOC. This primarily depended on the absence or presence of high surface area clay and iron oxide minerals and on the soil pH. Soil mineralogy did not appear to have a major impact on the composition of soil organic matter (SOM) with depth. The results suggest that when carbon sequestration practices in Northern Ireland are considered, soils derived from basalts are likely to acquire greater carbon concentrations than soils from other lithologie
Exploring a string-like landscape
We explore inflationary trajectories within randomly-generated
two-dimensional potentials, considered as a toy model of the string landscape.
Both the background and perturbation equations are solved numerically, the
latter using the two-field formalism of Peterson and Tegmark which fully
incorporates the effect of isocurvature perturbations. Sufficient inflation is
a rare event, occurring for only roughly one in potentials. For models
generating sufficient inflation, we find that the majority of runs satisfy
current constraints from WMAP. The scalar spectral index is less than 1 in all
runs. The tensor-to-scalar ratio is below the current limit, while typically
large enough to be detected by next-generation CMB experiments and perhaps also
by Planck. In many cases the inflationary consistency equation is broken by the
effect of isocurvature modes.Comment: 24 pages with 8 figures incorporated, matches version accepted by
JCA
Soil natural capital in Europe; a framework for state and change assessment
Soils underpin our existence through food production and represent the largest terrestrial carbon store. Understanding soil state-and-change in response to climate and land use change is a major challenge. Our aim is to bridge the science-policy interface by developing a natural capital accounting structure for soil, for example, attempting a mass balance between soil erosion and production, which indicates that barren land, and woody crop areas are most vulnerable to potential soil loss. We test out our approach using earth observation, modelling and ground based sample data from the European Unionâs Land Use/Cover Area frame statistical Survey (LUCAS) soil monitoring program. Using land cover change data for 2000â2012 we are able to identify land covers susceptible to change, and the soil resources most at risk. Tree covered soils are associated with the highest carbon stocks, and are on the increase, while areas of arable crops are declining, but artificial surfaces are increasing. The framework developed offers a substantial step forward, demonstrating the development of biophysical soil accounts that can be used in wider socio-economic and policy assessment; initiating the development of an integrated soil monitoring approach called for by the United Nations Intergovernmental Technical Panel on Soils
Distribution and speciation of phosphorus in foreshore sediments of the Thames estuary, UK
Estuarine sediments can be a source of Phosphorus (P) to coastal waters, contributing to nutrient budgets and geochemical cycles. In this work, the concentration and speciation of P in 47 cores were examined from the inter-tidal mud flats of the tidal river Thames (~ 120 km). Results of P concentration and speciation were combined with published data relating to known sediment dynamics and water chemistry (salinity) within the estuary to produce a conceptual model of sediment-P behaviour. Results demonstrated significant P desorption occurring after sediment passed through the Estuarine Turbidity Maximum and when the salinity of the river water exceeded ~ 6 ppt. It was found that organic P was desorbed to a greater extent than inorganic P in the lower estuary. Models were used to identify those geochemical parameters that contributed to the Total P (R2 = 0.80), oxalate extractable P (R2 = 0.80) and inorganic P (R2 = 0.76) concentrations within the Thames estuary
Assessment of suspended sediment export and dynamics using inâline turbidity sensors and time series statistical models
The Coln is an ecologically sensitive river in a limestone dominated catchment with no major tributaries. Three in-line turbidity sensors were installed to monitor changes in the dynamics of suspended sediment transport from headwaters to the confluence. The aims were to (i) provide estimates of yield (tâkmâ2 yearâ1) and likely drivers of suspended sediment over ~3 years and (ii) assess turbidity dynamics during storm events in different parts of the catchment. In addition, the sensor installation allowed a novel wavelet analysis based on identifying groups of turbidity peaks to estimate transport times of suspended sediment through the catchment. Yearly suspended sediment yields calculated for the upper catchment were typically less than 4 tâhaâ1 yearâ1 being similar to other UK limestone or chalk-based rivers. Time series autoregressive integrated moving average models including explanatory variable regression modelling indicated that river discharge, groundwater level and water temperature were all significant predictors of turbidity levels throughout the year. However, high model residuals demonstrate that the models failed to capture random turbidity events. Five parts of the time series data were used to examine sediment dynamics. Plots of scaled discharge verses turbidity demonstrated that in the upper catchment, after initial suspended sediment generation, sediment quickly became limited. In the lower catchment, hysteresis analysis suggested that sediment dilution occurred, due to increasing base flow. The novel wavelet analysis demonstrated that during winter âsediment eventsâ identified as groups of turbidity peaks, took ~18âh to pass from the first sensor in the upper catchment to the second sensor (10.3 km downstream of sensor 1) and 24âh to the third sensor (23.3 km from sensor 1). The work demonstrates the potential for using multiple turbidity sensors and time series statistical techniques in developing greater understanding of suspended sediment dynamics and associated poor water quality in ecologically sensitive rivers
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