| 1. |
- Mojumdar, Enamul Haque, et al.
(författare)
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Probing skin barrier recovery on molecular level following acute wounds : An in vivo/ex vivo study on pigs
- 2021
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Ingår i: Biomedicines. - : MDPI AG. - 2227-9059. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- Proper skin barrier function is paramount for our survival, and, suffering injury, there is an acute need to restore the lost barrier and prevent development of a chronic wound. We hypothesize that rapid wound closure is more important than immediate perfection of the barrier, whereas specific treatment may facilitate perfection. The aim of the current project was therefore to evaluate the quality of restored tissue down to the molecular level. We used Göttingen minipigs with a multi-technique approach correlating wound healing progression in vivo over three weeks, monitored by classical methods (e.g., histology, trans-epidermal water loss (TEWL), pH) and subsequent physicochemical characterization of barrier recovery (i.e., small and wide-angle X-ray diffraction (SWAXD), polarization transfer solid-state NMR (PTssNMR), dynamic vapor sorption (DVS), Fourier transform infrared (FTIR)), providing a unique insight into molecular aspects of healing. We conclude that although acute wounds sealed within two weeks as expected, molecular investigation of stratum corneum (SC) revealed a poorly developed keratin organization and deviations in lipid lamellae formation. A higher lipid fluidity was also observed in regenerated tissue. This may have been due to incomplete lipid conversion during barrier recovery as glycosphingolipids, normally not present in SC, were indicated by infrared FTIR spectroscopy. Evidently, a molecular approach to skin barrier recovery could be a valuable tool in future development of products targeting wound healing.
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| 2. |
- Morén, Ida, et al.
(författare)
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Cross‐Validating Hydromechanical Models and Tracer Test Assessments of Hyporheic Exchange Flow in Streams With Different Hydromorphological Characteristics
- 2021
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Ingår i: Water resources research. - : American Geophysical Union (AGU). - 0043-1397 .- 1944-7973. ; 57:12
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Tidskriftsartikel (refereegranskat)abstract
- Hyporheic exchange flow (HEF) can generally be quantified through two different approaches. The first approach, which is deductive, entails physically based models, supported with relevant observations. The second approach includes inductive assessments of stream tracer tests using solute transport models, which provide a useful mathematical framework that allows for upscaling of results, but included parameters often have a vague physical base, which limits the possibilities of generalizing results using independent hydromorphological observations. To better understand how the physical basis of HEF-quantifying parameters relates to stream hydromorphology at different spatial scales, we cross-validated the results from (a) tracer test assessments using a 1D solute transport model that accounts for HEF and (b) an independent hydromechanical model that represents HEF driven by multiscale pressure gradients along the streambed interface. To parameterize the models, topographical surveys, tracer tests, and streambed hydraulic conductivity measurements were performed in 10 stream reaches, differing in terms of geomorphology, slope, and discharge. The results show that the models were cross-validated in terms of the average exchange velocity, providing a plausible physical explanation for this parameter in small alluvial streams with low discharges, shallow depth, and moderate slopes. However, the hydromechanical model generally resulted in wider residence time distributions and occasionally higher average residence times compared to the tracer test assessments. From the cross-validated multiscale hydromechanical model, we learned that water surface profile variations were the main drivers of HEF in all investigated streams and that spatial scales between 20 cm and 5 m dominated the estimated HEF velocity.
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| 3. |
- Morén, Ida, et al.
(författare)
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Design of Remediation Actions for Nutrient Mitigation in the Hyporheic Zone
- 2017
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Ingår i: Water resources research. - : American Geophysical Union (AGU). - 0043-1397 .- 1944-7973. ; 53:11, s. 8872-8899
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Tidskriftsartikel (refereegranskat)abstract
- Although hyporheic exchange has been shown to be of great importance for the overall water quality of streams, it is rarely considered quantitatively in stream remediation projects. A main driver of hyporheic exchange is the hydraulic head fluctuation along the streambed, which can be enhanced by modifications of the streambed topography. Here we present an analytical 2-D spectral subsurface flow model to estimate the hyporheic exchange associated with streambed topographies over a wide range of spatial scales; a model that was validated using tracer-test-results and measurements of hydraulic conductivity. Specifically, engineered steps in the stream were shown to induce a larger hyporheic exchange velocity and shorter hyporheic residence times compared to the observed topography in Tullstorps Brook, Sweden. Hyporheic properties were used to parameterize a longitudinal transport model that accounted for reactions in terms of first-order decay and instantaneous adsorption. Theoretical analyses of the mitigation effect for nitrate due to denitrification in the hyporheic zone show that there is a Damkohler number of the hyporheic zone, associated with several different stream geomorphologies, that optimizes nitrate mass removal on stream reach scale. This optimum can be limited by the available hydraulic head gradient given by the slope of the stream and the geological constraints of the streambed. The model illustrates the complex interactions between design strategies for nutrient mitigation, hyporheic flow patterns, and stream biogeochemistry and highlights the importance to diagnose a stream prior remediation, specifically to evaluate if remediation targets are transport or reaction controlled.
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| 4. |
- Morén, Ida, et al.
(författare)
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Geographic and hydromorphologic controls on interactions between hyporheic flow and discharging deep groundwater
- 2023
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Ingår i: Hydrogeology Journal. - : Springer Nature. - 1431-2174 .- 1435-0157. ; 31:3, s. 537-555
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Tidskriftsartikel (refereegranskat)abstract
- Hyporheic exchange flow (HEF) at the streambed–water interface (SWI) has been shown to impact the pattern and rate of discharging groundwater flow (GWF) and the consequential transport of heat, solutes and contaminants from the subsurface into streams. However, the control of geographic and hydromorphological catchment characteristics on GWF–HEF interactions is still not fully understood. Here, the spatial variability in flow characteristics in discharge zones was investigated and averaged over three spatial scales in five geographically different catchments in Sweden. Specifically, the deep GWF discharge velocity at the SWI was estimated using steady-state numerical models, accounting for the real multiscale topography and heterogeneous geology, while an analytical model, based on power spectral analysis of the streambed topography and statistical assessments of the stream hydraulics, was used to estimate the HEF. The modeling resulted in large variability in deep GWF and HEF velocities, both within and between catchments, and a regression analysis was performed to explain this observed variability by using a set of independent variables representing catchment topography and geology as well as local stream hydromorphology. Moreover, the HEF velocity was approximately two orders of magnitude larger than the deep GWF velocity in most of the investigated stream reaches, indicating significant potential to accelerate the deep GWF velocity and reduce the discharge areas. The greatest impact occurred in catchments with low average slope and in reaches close to the catchment outlet, where the deep GWF discharge velocity was generally low.
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| 5. |
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| 6. |
- Morén, Ida
(författare)
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The influence of multiscale hyporheic flow on solute transport : Implications for stream restoration enhancing nitrogen removal
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Stream water that flows into and out of streambeds is called hyporheic exchange flow (HEF).It continuously interacts with groundwater and thereby affect the water quality of local streamreaches as well as downstream recipients by providing an environment where solutes andenergy can be retained and degraded. Because of anthropogenic activities, many streams andrivers have been physically, chemically and biologically degraded during the last centuries andnatural functions, such as HEF, have to some extent been lost. The general aim of this thesiswas to advance the understanding of the physical controls of HEF in small streams and toinvestigate how HEF influences solute reactive transport in streambeds and surface waternetworks before and after stream restoration. To reach the aim, the consistency and deviationbetween HEF parameters evaluated with two common approaches were investigated in tendifferent alluvial streams with low discharge, shallow depth and moderate slope. The twoapproaches were: 1) developing and using a deductive hydro-mechanical model to assessed therelationship between the multiscale streambed geomorphology and the reach scale averageHEF parameters, and 2) evaluating HEF parameters from in-stream tracer tests using a 1Dlongitudinal transport model. The relatively high consistency between the approaches connectstheories that previously have been relatively fragmented and provides a tool for upscaling(parameterizing) of HEF in solute transport models over stream networks based onindependent observations of stream topography, streambed sediment properties and in-streamhydraulics. Applying the modelling framework at the network scale and supporting it withcomprehensive datasets provided information regarding physical mechanisms and spatialvariability of HEF as well as its influence on longitudinal solute transport. Specifically, thefractal properties of the water surface profile were shown to represent the average HEF velocitywell. Furthermore, hydraulic head variations over shorter wavelengths (0.1-5 m) were found todrive the main part of the HEF and the static hydraulic head variations dominated over dynamichydraulic head variations as drivers of HEF in all investigated streams. Moreover, this thesishighlights the importance of the hyporheic zone as a bio-chemical and mechanical filter forstream water. It shows that common engineered stream restorations can influence HEF andimprove the water quality in local stream reaches as well as downstream recipients. Specifically,the thesis presents exact solutions to the nitrogen transport, which shows that the mass removalof nitrogen in the hyporheic zone is either transport or reaction limited and that the maximalremoval rate corresponds to an optimal hyporheic residence time and a typical denitrificationDamköhler number. The results also show that potential exists to reduce the agriculturalnitrogen load to the Baltic Sea by stream restorations that optimize the hyporheic residencetimes. However, the large spatiotemporal variability in the potential between reaches stressesthe importance for further studies on which processes that are driving HEF under specifichydromorphologic conditions and careful design of stream restoration measures at each localstream reach.
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| 7. |
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| 8. |
- Riml, Joakim, 1979-, et al.
(författare)
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Potential of stream restorations to enhance the hyporheic removal of agricultural nitrogen in Sweden
- 2024
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Ingår i: Ecological Engineering. - : Elsevier B.V.. - 0925-8574 .- 1872-6992. ; 201
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Tidskriftsartikel (refereegranskat)abstract
- Stream restoration has been advocated as a key strategy to restore the ecosystem functioning of degraded stream systems, mitigate excess nutrient concentrations and reduce export to downstream recipients. Specifically small agricultural streams are suitable for such restoration efforts due their disproportionate contribution to downstream nutrient loading and their large proportion of the total stream network length. However, large-scale assessments of both the current removal efficiencies in and the enhancement potential of these streams are generally lacking. Here, we used a physically based model framework supported by an extensive dataset to simulate the transport and removal of nitrogen (N) in all local agricultural streams in Sweden, equivalent to 70,000 km or 33.5% of the total mapped stream network. The framework assumed that N removal occurred predominantly by denitrification in the hyporheic zone and was utilized to quantify the current and potential removal as well as to assess the limiting conditions in terms of Damköhler numbers. The removal rates were shown to be highly variable with location, but the aggregated results indicated that the current removal for all assessed reaches was 13.1, 0.1 and 37.6% of their load during mean (MQ), mean high (MHQ) and mean low discharge (MLQ) conditions, respectively. The theoretical potential of N removal, i.e., the aggregated removal under the assumption of optimal hyporheic conditions was estimated to be 15.4, 1.9 and 62.1% during MQ, MHQ and MLQ, respectively. The study also comprised a detailed investigation along one single stream reach that displayed the ability of engineered restoration actions to alter the hyporheic residence times and, in the end, the hyporheic N-removal during different discharge conditions. Overall, our results indicated that in-stream restoration efforts aiming to enhance hyporheic functioning in small agricultural streams had a high potential to reduce terrestrial N export, especially if implemented over larger areas.
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