| 1. |
- Datry, T., et al.
(författare)
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A global analysis of terrestrial plant litter dynamics in non-perennial waterways
- 2018
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Ingår i: Nature Geoscience. - : Nature Publishing Group. - 1752-0894 .- 1752-0908. ; 11:7, s. 497-503
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Tidskriftsartikel (refereegranskat)abstract
- Perennial rivers and streams make a disproportionate contribution to global carbon (C) cycling. However, the contribution of intermittent rivers and ephemeral streams (IRES), which sometimes cease to flow and can dry completely, is largely ignored although they represent over half the global river network. Substantial amounts of terrestrial plant litter (TPL) accumulate in dry riverbeds and, upon rewetting, this material can undergo rapid microbial processing. We present the results of a global research collaboration that collected and analysed TPL from 212 dry riverbeds across major environmental gradients and climate zones. We assessed litter decomposability by quantifying the litter carbon-to-nitrogen ratio and oxygen (O2) consumption in standardized assays and estimated the potential short-term CO2 emissions during rewetting events. Aridity, cover of riparian vegetation, channel width and dry-phase duration explained most variability in the quantity and decomposability of plant litter in IRES. Our estimates indicate that a single pulse of CO2 emission upon litter rewetting contributes up to 10% of the daily CO2 emission from perennial rivers and stream, particularly in temperate climates. This indicates that the contributions of IRES should be included in global C-cycling assessments.
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| 2. |
- von Schiller, D., et al.
(författare)
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Sediment Respiration Pulses in Intermittent Rivers and Ephemeral Streams
- 2019
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Ingår i: Global Biogeochemical Cycles. - : American Geophysical Union (AGU). - 0886-6236 .- 1944-9224. ; 33:10, s. 1251-1263
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Tidskriftsartikel (refereegranskat)abstract
- Intermittent rivers and ephemeral streams (IRES) may represent over half the global stream network, but their contribution to respiration and carbon dioxide (CO2) emissions is largely undetermined. In particular, little is known about the variability and drivers of respiration in IRES sediments upon rewetting, which could result in large pulses of CO2. We present a global study examining sediments from 200 dry IRES reaches spanning multiple biomes. Results from standardized assays show that mean respiration increased 32-fold to 66-fold upon sediment rewetting. Structural equation modeling indicates that this response was driven by sediment texture and organic matter quantity and quality, which, in turn, were influenced by climate, land use, and riparian plant cover. Our estimates suggest that respiration pulses resulting from rewetting of IRES sediments could contribute significantly to annual CO2 emissions from the global stream network, with a single respiration pulse potentially increasing emission by 0.2-0.7%. As the spatial and temporal extent of IRES increases globally, our results highlight the importance of recognizing the influence of wetting-drying cycles on respiration and CO2 emissions in stream networks.
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| 3. |
- Shumilova, Oleksandra, et al.
(författare)
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Simulating rewetting events in intermittent rivers and ephemeral streams : A global analysis of leached nutrients and organic matter
- 2019
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Ingår i: Global Change Biology. - : WILEY. - 1354-1013 .- 1365-2486. ; 25:5, s. 1591-1611
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Tidskriftsartikel (refereegranskat)abstract
- Climate change and human pressures are changing the global distribution and the extent of intermittent rivers and ephemeral streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physico-chemical changes (preconditioning), and periods of flow resumption, when these substrates are rewetted and release pulses of dissolved nutrients and organic matter (OM). However, there are no estimates of the amounts and quality of leached substances, nor is there information on the underlying environmental constraints operating at the global scale. We experimentally simulated, under standard laboratory conditions, rewetting of leaves, riverbed sediments, and epilithic biofilms collected during the dry phase across 205 IRES from five major climate zones. We determined the amounts and qualitative characteristics of the leached nutrients and OM, and estimated their areal fluxes from riverbeds. In addition, we evaluated the variance in leachate characteristics in relation to selected environmental variables and substrate characteristics. We found that sediments, due to their large quantities within riverbeds, contribute most to the overall flux of dissolved substances during rewetting events (56%-98%), and that flux rates distinctly differ among climate zones. Dissolved organic carbon, phenolics, and nitrate contributed most to the areal fluxes. The largest amounts of leached substances were found in the continental climate zone, coinciding with the lowest potential bioavailability of the leached OM. The opposite pattern was found in the arid zone. Environmental variables expected to be modified under climate change (i.e. potential evapotranspiration, aridity, dry period duration, land use) were correlated with the amount of leached substances, with the strongest relationship found for sediments. These results show that the role of IRES should be accounted for in global biogeochemical cycles, especially because prevalence of IRES will increase due to increasing severity of drying events.
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| 4. |
- Jiménez-Murcia, Susana, et al.
(författare)
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A comparison of DSM-IV-TR and DSM-5 diagnostic criteria for gambling disorder in a large clinical sample
- 2019
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Ingår i: Frontiers in Psychology. - : Frontiers Media SA. - 1664-1078. ; 10:APR
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Tidskriftsartikel (refereegranskat)abstract
- Background and aims: Gambling-related crimes are known to be associated with gambling disorder (GD). Due to a lack of consensus in the scientific community regarding the relevance of this diagnostic criterion, it was removed from the DSM-5. The primary aim of this study was to investigate through structural equation modeling (SEM) whether higher GD severity in treatment-seeking GD patients with a criminal record is mediated through the illegal acts criterion itself, or whether it can be better explained by other related clinical factors. Methods: An initial sample of 2,081 patients seeking treatment for gambling problems was included in the sample. SEM was used to evaluate the mediational role of the illegal acts criterion between the sex, age and personality traits, gambling severity, and comorbid depression levels. Comparisons between patients with coinciding and divergent DSM criterion for GD diagnosis were carried out. Results: Illegal acts mediated the relationship between personality traits and GD severity: younger age, high levels of novelty seeking, and low levels of self-transcendence increased the risk of endorsing the illegal acts criterion. No differences between coincident-divergent groups in terms of DSM-IV and DSM-5 diagnosis were found with regards to sex (p=.878), education level (p=.387) or civil status (p=.792). Discussion and conclusions: The results obtained in the present study offer new insights into the utility of using a history of illegal acts, their different personality characteristics and psychopathology to categorize GD patients. Our findings suggest that patients who engage in criminal behavior may require a more comprehensive intervention.
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| 5. |
- Jiménez-Murcia, Susana, et al.
(författare)
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Treatment outcome in male Gambling Disorder patients associated with alcohol use
- 2016
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Ingår i: Frontiers in Psychology. - : Frontiers Media SA. - 1664-1078. ; 7:MAR
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Tidskriftsartikel (refereegranskat)abstract
- Aims: The primary objective of this study was to analyze the association between alcohol consumption and short-term response to treatment (post intervention) in male patients with gambling disorder enrolled in a group cognitive behavioral therapy (CBT) program. Methods: The sample consisted of 111 male individuals with a diagnosis of Gambling Disorder, with a mean age of 45 years (SD = 12.2). All participants were evaluated by a comprehensive assessment battery and assigned to CBT groups of 10-14 patients attending 16 weekly outpatient sessions lasting 90 min each. Results: The highest mean pre- and post-therapy differences were recorded for the alcohol risk/dependence group on the obsessive/compulsive and anxiety dimensions of the SCL-90-R. As regards the presence of relapses and dropouts over the course of the CBT sessions, the results show a significant association with moderate effect size: Patients with risk consumption or alcohol dependence were more likely to present poor treatment outcomes. Conclusions: Alcohol abuse was frequent in GD, especially in patients with low family income and high accumulated debts. High levels of somatization and high overall psychopathology (measured by the SCL-90-R) were associated with increased risk of alcohol abuse. Alcohol abuse was also associated with poor response to treatment.
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| 6. |
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