| 1. |
- Lozano, Rafael, et al.
(författare)
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Measuring progress from 1990 to 2017 and projecting attainment to 2030 of the health-related Sustainable Development Goals for 195 countries and territories: a systematic analysis for the Global Burden of Disease Study 2017
- 2018
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Ingår i: The Lancet. - : Elsevier. - 1474-547X .- 0140-6736. ; 392:10159, s. 2091-2138
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Tidskriftsartikel (refereegranskat)abstract
- Background: Efforts to establish the 2015 baseline and monitor early implementation of the UN Sustainable Development Goals (SDGs) highlight both great potential for and threats to improving health by 2030. To fully deliver on the SDG aim of “leaving no one behind”, it is increasingly important to examine the health-related SDGs beyond national-level estimates. As part of the Global Burden of Diseases, Injuries, and Risk Factors Study 2017 (GBD 2017), we measured progress on 41 of 52 health-related SDG indicators and estimated the health-related SDG index for 195 countries and territories for the period 1990–2017, projected indicators to 2030, and analysed global attainment. Methods: We measured progress on 41 health-related SDG indicators from 1990 to 2017, an increase of four indicators since GBD 2016 (new indicators were health worker density, sexual violence by non-intimate partners, population census status, and prevalence of physical and sexual violence [reported separately]). We also improved the measurement of several previously reported indicators. We constructed national-level estimates and, for a subset of health-related SDGs, examined indicator-level differences by sex and Socio-demographic Index (SDI) quintile. We also did subnational assessments of performance for selected countries. To construct the health-related SDG index, we transformed the value for each indicator on a scale of 0–100, with 0 as the 2·5th percentile and 100 as the 97·5th percentile of 1000 draws calculated from 1990 to 2030, and took the geometric mean of the scaled indicators by target. To generate projections through 2030, we used a forecasting framework that drew estimates from the broader GBD study and used weighted averages of indicator-specific and country-specific annualised rates of change from 1990 to 2017 to inform future estimates. We assessed attainment of indicators with defined targets in two ways: first, using mean values projected for 2030, and then using the probability of attainment in 2030 calculated from 1000 draws. We also did a global attainment analysis of the feasibility of attaining SDG targets on the basis of past trends. Using 2015 global averages of indicators with defined SDG targets, we calculated the global annualised rates of change required from 2015 to 2030 to meet these targets, and then identified in what percentiles the required global annualised rates of change fell in the distribution of country-level rates of change from 1990 to 2015. We took the mean of these global percentile values across indicators and applied the past rate of change at this mean global percentile to all health-related SDG indicators, irrespective of target definition, to estimate the equivalent 2030 global average value and percentage change from 2015 to 2030 for each indicator. Findings: The global median health-related SDG index in 2017 was 59·4 (IQR 35·4–67·3), ranging from a low of 11·6 (95% uncertainty interval 9·6–14·0) to a high of 84·9 (83·1–86·7). SDG index values in countries assessed at the subnational level varied substantially, particularly in China and India, although scores in Japan and the UK were more homogeneous. Indicators also varied by SDI quintile and sex, with males having worse outcomes than females for non-communicable disease (NCD) mortality, alcohol use, and smoking, among others. Most countries were projected to have a higher health-related SDG index in 2030 than in 2017, while country-level probabilities of attainment by 2030 varied widely by indicator. Under-5 mortality, neonatal mortality, maternal mortality ratio, and malaria indicators had the most countries with at least 95% probability of target attainment. Other indicators, including NCD mortality and suicide mortality, had no countries projected to meet corresponding SDG targets on the basis of projected mean values for 2030 but showed some probability of attainment by 2030. For some indicators, including child malnutrition, several infectious diseases, and most violence measures, the annualised rates of change required to meet SDG targets far exceeded the pace of progress achieved by any country in the recent past. We found that applying the mean global annualised rate of change to indicators without defined targets would equate to about 19% and 22% reductions in global smoking and alcohol consumption, respectively; a 47% decline in adolescent birth rates; and a more than 85% increase in health worker density per 1000 population by 2030. Interpretation: The GBD study offers a unique, robust platform for monitoring the health-related SDGs across demographic and geographic dimensions. Our findings underscore the importance of increased collection and analysis of disaggregated data and highlight where more deliberate design or targeting of interventions could accelerate progress in attaining the SDGs. Current projections show that many health-related SDG indicators, NCDs, NCD-related risks, and violence-related indicators will require a concerted shift away from what might have driven past gains—curative interventions in the case of NCDs—towards multisectoral, prevention-oriented policy action and investments to achieve SDG aims. Notably, several targets, if they are to be met by 2030, demand a pace of progress that no country has achieved in the recent past. The future is fundamentally uncertain, and no model can fully predict what breakthroughs or events might alter the course of the SDGs. What is clear is that our actions—or inaction—today will ultimately dictate how close the world, collectively, can get to leaving no one behind by 2030.
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| 2. |
- Attermeyer, Katrin, et al.
(författare)
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Carbon dioxide fluxes increase from day to night across European streams
- 2021
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Ingår i: Communications Earth & Environment. - : Springer Nature. - 2662-4435. ; 2:1
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Tidskriftsartikel (refereegranskat)abstract
- Globally, inland waters emit over 2 Pg of carbon per year as carbon dioxide, of which the majority originates from streams and rivers. Despite the global significance of fluvial carbon dioxide emissions, little is known about their diel dynamics. Here we present a large-scale assessment of day- and night-time carbon dioxide fluxes at the water-air interface across 34 European streams. We directly measured fluxes four times between October 2016 and July 2017 using drifting chambers. Median fluxes are 1.4 and 2.1mmolm(-2) h(-1) at midday and midnight, respectively, with night fluxes exceeding those during the day by 39%. We attribute diel carbon dioxide flux variability mainly to changes in the water partial pressure of carbon dioxide. However, no consistent drivers could be identified across sites. Our findings highlight widespread day-night changes in fluvial carbon dioxide fluxes and suggest that the time of day greatly influences measured carbon dioxide fluxes across European streams. Diel patterns can greatly impact total stream carbon dioxide emissions, with 39% greater carbon dioxide flux during the night-time relative to the day-time, according to a study of 34 streams across Europe.
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| 3. |
- Blackburn, Meredith, et al.
(författare)
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Evaluating hillslope and riparian contributions to dissolved nitrogen (N) export from a boreal forest catchment
- 2017
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Ingår i: Journal of Geophysical Research: Biogeosciences. - : AMER GEOPHYSICAL UNION. - 2169-8953 .- 2169-8961. ; 122, s. 324-339
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Tidskriftsartikel (refereegranskat)abstract
- Catchment science has long held that the chemistry of small streams reflects the landscapes they drain. However, understanding the contribution of different landscape units to stream chemistry remains a challenge which frequently limits our understanding of export dynamics. For limiting nutrients such as nitrogen (N), an implicit assumption is that the most spatially extensive landscape units (e.g., uplands) act as the primary sources to surface waters, while near-stream zones function more often as sinks. These assumptions, based largely on studies in high-gradient systems or in regions with elevated inputs of anthropogenic N, may not apply to low-gradient, nutrient-poor, and peat-rich catchments characteristic of many northern ecosystems. We quantified patterns of N mobilization along a hillslope transect in a northern boreal catchment to assess the extent to which organic matter-rich riparian soils regulate the flux of N to streams. Contrary to the prevailing view of riparian functioning, we found that near-stream, organic soils supported concentrations and fluxes of ammonium (NH4+) and dissolved organic nitrogen that were much higher than the contributing upslope forest soils. These results suggest that stream N chemistry is connected to N mobilization and mineralization within the riparian zone rather than the wider landscape. Results further suggest that water table fluctuation in near-surface riparian soils may promote elevated rates of net N mineralization in these landscapes.
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| 4. |
- Bravo, Andrea G., et al.
(författare)
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The interplay between total mercury, methylmercury and dissolved organic matter in fluvial systems : A latitudinal study across Europe
- 2018
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Ingår i: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 144, s. 172-182
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Tidskriftsartikel (refereegranskat)abstract
- Large-scale studies are needed to identify the drivers of total mercury (THg) and monomethyl-mercury (MeHg) concentrations in aquatic ecosystems. Studies attempting to link dissolved organic matter (DOM) to levels of THg or MeHg are few and geographically constrained. Additionally, stream and river systems have been understudied as compared to lakes. Hence, the aim of this study was to examine the influence of DOM concentration and composition, morphological descriptors, land uses and water chemistry on THg and MeHg concentrations and the percentage of THg as MeHg (%MeHg) in 29 streams across Europe spanning from 41°N to 64°N. THg concentrations (0.06–2.78 ng L−1) were highest in streams characterized by DOM with a high terrestrial soil signature and low nutrient content. MeHg concentrations (7.8–159 pg L−1) varied non-systematically across systems. Relationships between DOM bulk characteristics and THg and MeHg suggest that while soil derived DOM inputs control THg concentrations, autochthonous DOM (aquatically produced) and the availability of electron acceptors for Hg methylating microorganisms (e.g. sulfate) drive %MeHg and potentially MeHg concentration. Overall, these results highlight the large spatial variability in THg and MeHg concentrations at the European scale, and underscore the importance of DOM composition on mercury cycling in fluvial systems.
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| 5. |
- Bravo, Andrea G., et al.
(författare)
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The interplay between total mercury, methylmercury and dissolved organic matter in fluvial systems : A latitudinal study across Europe
- 2018
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Ingår i: Water Research. - : Pergamon. - 0043-1354 .- 1879-2448. ; 144, s. 172-182
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Tidskriftsartikel (refereegranskat)abstract
- Large-scale studies are needed to identify the drivers of total mercury (THg) and monomethyl-mercury (MeHg) concentrations in aquatic ecosystems. Studies attempting to link dissolved organic matter (DOM) to levels of THg or MeHg are few and geographically constrained. Additionally, stream and river systems have been understudied as compared to lakes. Hence, the aim of this study was to examine the influence of DOM concentration and composition, morphological descriptors, land uses and water chemistry on THg and MeHg concentrations and the percentage of THg as MeHg (%MeHg) in 29 streams across Europe spanning from 41°N to 64 °N. THg concentrations (0.06–2.78 ng L−1) were highest in streams characterized by DOM with a high terrestrial soil signature and low nutrient content. MeHg concentrations (7.8–159 pg L−1) varied non-systematically across systems. Relationships between DOM bulk characteristics and THg and MeHg suggest that while soil derived DOM inputs control THg concentrations, autochthonous DOM (aquatically produced) and the availability of electron acceptors for Hg methylating microorganisms (e.g. sulfate) drive %MeHg and potentially MeHg concentration. Overall, these results highlight the large spatial variability in THg and MeHg concentrations at the European scale, and underscore the importance of DOM composition on mercury cycling in fluvial systems.
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| 6. |
- Ecke, Frauke, et al.
(författare)
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Meta-analysis of environmental effects of beaver in relation to artificial dams
- 2017
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Ingår i: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 12
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Forskningsöversikt (refereegranskat)abstract
- Globally, artificial river impoundment, nutrient enrichment and biodiversity loss impair freshwater ecosystem integrity. Concurrently, beavers, ecosystem engineers recognized for their ability to construct dams and create ponds, are colonizing sites across the Holarctic after widespread extirpation in the 19th century, including areas outside their historical range. This has the potential to profoundly alter hydrology, hydrochemistry and aquatic ecology in both newly colonized and recolonized areas. To further our knowledge of the effects of beaver dams on aquatic environments, we extracted 1366 effect sizes from 89 studies on the impoundment of streams and lakes. Effects were assessed for 16 factors related to hydrogeomorphology, biogeochemistry, ecosystem functioning and biodiversity. Beaver dams affected concentrations of organic carbon in water, mercury in water and biota, sediment conditions and hydrological properties. There were no overall adverse effects caused by beaver dams or ponds on salmonid fish. Age was an important determinant of effect magnitude. While young ponds were a source of phosphorus, there was a tendency for phosphorus retention in older systems. Young ponds were a source methylmercury in water, but old ponds were not. To provide additional context, we also evaluated similarities and differences between environmental effects of beaver-constructed and artificial dams (767 effect sizes from 75 studies). Both are comparable in terms of effects on, for example, biodiversity, but have contrasting effects on nutrient retention and mercury. These results are important for assessing the role of beavers in enhancing and/or degrading ecological integrity in changing Holarctic freshwater systems.
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| 7. |
- Erlandsson, M., et al.
(författare)
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Spatial and temporal variations of base cation release from chemical weathering on a hillslope scale
- 2016
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Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 441, s. 1-13
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Tidskriftsartikel (refereegranskat)abstract
- Cation release rates to catchment runoff from chemical weathering were assessed using an integrated catchment model that included the soil's unsaturated, saturated and riparian zones. In-situ mineral dissolution rates were calculated in these zones as a function of pH, aluminum and dissolved organic carbon (DOC) concentrations along a hillslope in Northern Sweden where soil water was monitored over nine years. Three independent sets of mineral dissolution equations of varying complexity were used: PROFILE, Transition-State Theory (TST), and the Palandri & Kharaka database. Normalization of the rate-coefficients was necessary to compare the equations, as published rate-coefficients gave base cation release rates differing by several orders of magnitude. After normalizing the TST- and Palandri & Kharaka-rate coefficients to match the base cation release rates calculated from the PROFILE-equations, calculated Ca2 + and Mg2 + release rates are consistent with mass balance calculations, whereas those of Na+ and K+ are overestimated. Our calculations further indicate that a significant proportion of base cations are released from the organic soils in the near-stream zone, in part due to its finer texture. Of the three sets of rate equations, the base cation release rates calculated from the normalized TST-equations were more variable than those calculated using the other two sets of equations, both spatially and temporally, due to its higher sensitivity to pH. In contrast, the normalized Palandri & Kharaka-equations were more sensitive to variations in soil temperature.
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| 8. |
- Futter, Martyn, et al.
(författare)
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Retention efficiency for microplastic in a landscape estimated from empirically validated dynamic model predictions
- 2024
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Ingår i: Journal of Hazardous Materials. - 0304-3894 .- 1873-3336. ; 464
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Tidskriftsartikel (refereegranskat)abstract
- Soils are recipients of microplastic that can be subsequently transferred to the sea. Land sources dominate inputs to the ocean, but knowledge gaps about microplastic retention by land hinder assessments of input rates. Here we present the first empirical evaluation of a dynamic microplastic fate model operating at landscape level. This mechanistic model accounts for hydrology, soil and sediment erosion, particle characteristics and behavior. We predict microplastic concentrations in water and sediments of the Henares river (Spain) within the measurement uncertainty boundaries (error factors below 2 and 10, respectively). Microplastic export from land and discharge by river fluctuates in a non-linear manner with precipitation and runoff variability. This indicates the need of accurate dynamic descriptions of soil and stream hydrology even when modeling microplastic fate and transport in generic scenarios and at low spatio-temporal resolution. A time-averaged landscape retention efficiency was calculated showing 20-50% of the microplastics added to the catchment over a multiannual period were retained. While the analysis reveals persistent uncertainties and knowledge gaps on microplastic sources to the catchment, these results contribute to the quantitative understanding of the role of terrestrial environments in accumulating microplastics, delaying their transport to the sea.
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| 9. |
- Hoffmeister, Svenja, et al.
(författare)
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Evaluating the accuracy of two in-situ optical sensors to estimate DOC concentrations for drinking water production
- 2020
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Ingår i: Environmental Science: Water Research and Technology. - : Royal Society of Chemistry (RSC). - 2053-1419 .- 2053-1400. ; 6:10, s. 2891-2901
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Tidskriftsartikel (refereegranskat)abstract
- Two in situ optical sensors, a single-excitation fluorescence-based sensor (fDOM) mounted on a multi-parameter EXO2 sonde (YSI), and a stand-alone, multispectral absorbance-based instrument (spectro::lyser, scan Messtechnik GmbH), were evaluated for their capability to (i) estimate river dissolved organic carbon (DOC) concentrations and (ii) provide oversight of drinking water production. The sensors were deployed between March and November 2017 in the river Fyris, which drains a mixed forested and agricultural 2003 km2 catchment and serves as a drinking water source by managed aquifer recharge. Grab samples were collected every 2 to 3 weeks and compared with logged sensor data collected at 15 minute intervals. The fDOM probe signal was used to estimate DOC concentrations in the range of 10.4 to 24.4 mg L−1 using linear regression (R2 = 0.71, RMSE = 2.5 mg L−1), after correction for temperature, turbidity and inner-filter effects. Temporal changes in DOC character associated with the mixed land use landscape, as indicated by optical indices, reduced this sensor accuracy for estimating DOC concentration. Nevertheless, humic substance concentrations, the fraction of DOC that is preferentially removed during artificial infiltration, were well captured. The spectrolyser signal was used to establish a 2-component partial least square model that captured DOC fluctuations from 10.2 to 29.4 mg L−1 (R2 = 0.92; RMSE = 1.3 mg L−1). This multiple-wavelength model (220 to 720 nm) effectively handled the changes in DOC composition while accurately estimating DOC concentrations. This study explores the advantages and limitations of optical sensors for their use in managed aquifer recharge and drinking water production in relation to DOC levels.
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| 10. |
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| 11. |
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| 12. |
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| 13. |
- Lannergård, Emma, et al.
(författare)
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An evaluation of high frequency turbidity as a proxy for riverine total phosphorus concentrations
- 2019
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 651, s. 103-113
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Tidskriftsartikel (refereegranskat)abstract
- Surface water eutrophication resulting from excessive phosphorus (P) inputs is one of today's most challenging environmental issues. Riverine total phosphorus (TP) concentrations have high temporal variability, which complicates flux estimation. We evaluated the usefulness of high frequency in-situ turbidity measurements as a proxy for TP in Savjaan, a river draining a mixed land use catchment (722 km(2)) in central Sweden. Turbidity was monitored every 10th-15th minute during 6 consecutive years (2012-2017). Linear regression showed a good relationship between high frequency turbidity and TP (r(2) = 0.64) and could hence be used for comparison of flux estimation methods. Predictive power of the turbidity-TP relationship was not improved by adding seasons, hydrograph rising/falling limb or high/lowstreamdischarge to the model which argues for a single transfer function relating turbidity and TP. Both TP and turbidity were log-normally distributed. However, flux estimates were sensitive to data transformation; predicted TP concentrations and fluxes based on log-transformed data were biased towards lower concentrations and fluxes compared to non-transformed data. In five of six years grab sample and high frequency estimated TP fluxes were similar (grab sample estimates-10% to + 13% P transport compared to high frequency flux estimates). The exception was in 2013, when a 50-year spring flood occurred, and the grab sample estimated flux was 56% larger than that estimated from high frequency data. Thus, the flux comparisons were mostly affected by stream discharge, which underlines the importance of capturing high discharge episodes with, e.g. in situ sensors. While uncertainties regarding the use of turbidity as a proxy for TP remain, it is clear that credible water chemistry data can be obtained with current high frequency sensors. We conclude that high frequency data can be used to better understand catchment response to external pressures and gain insights into water quality that will be missed with grab sampling. (C) 2018 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license.
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| 14. |
- Ledesma, Jose, et al.
(författare)
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Aquatic DOC export from subarctic Atlantic blanket bog in Norway is controlled by seasalt deposition, temperature and precipitation
- 2016
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Ingår i: Biogeochemistry. - : Springer Science and Business Media LLC. - 0168-2563 .- 1573-515X. ; 127, s. 305-321
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Tidskriftsartikel (refereegranskat)abstract
- Comprehensive and credible peatland carbon budgets, needed for global carbon accounting, must include lateral aquatic organic carbon export. Here, we quantify aquatic dissolved organic carbon (DOC) export for an Atlantic bog in subarctic Norway, the Andøya peatland, and test for sensitivity to climatic drivers. Hydrology, DOC concentrations and DOC export were simulated for 2000–2013 using the process-based catchment model Integrated Catchments model for Carbon(INCA-C), calibrated to site-specific water chemistry and hydrology (2011–2014) using readily-available data on temperature, precipitation and seasalt deposition. Measured streamwater DOC declined under seasalt episodes and was strongly positively related to temperature. Model calibrations successfully reproduced the water balance, variation in runoff (R2=0.67; Nash–Sutcliffe model efficiency NS=0.67) and DOC concentrations (R2=0.85; NS=0.84). The most sensitive model parameters related to temperature-sensitivity of DOC production and DOC (de)sorption sensitivity to seasalts. Model uncertainty related to parameter space was similar to interannual variation in DOC export. Mean annual modelled DOC export was 7.2±0.7g C m−2 year−1, roughly 35% of the net land–atmospheric CO2 exchange at Andøya from 2009 to 2012 (estimated elsewhere). Current and antecedent mean temperature and precipitation were strong drivers of seasonal modelled DOC export, implying that warmer and wetter summers will lead to more DOC export. Evaluation of similar climate impacts on net peatland carbon accumulation requires additional exploration of the climate-sensitivity of land–atmosphere fluxes of CO2 and methane. Process-based models are valuable tools to account for lateral DOC exports in carbon balances of northern peatlands, especially where long-term monitoring data are lacking.
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| 15. |
- Ledesma, Jose
(författare)
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Biogeochemical processes in forest riparian zones : conceptualizing function and heterogeneity in boreal catchments
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The area of interaction between terrestrial and aquatic environments, i.e. the riparian zone (RZ), has long been recognized as an important landscape feature from both scientific and management perspectives. Surface water quality is to a great extent regulated by substances exported from RZs. Boreal forest RZs are characterized by high organic matter content, which drives important biogeochemical processes. The overall objective of this thesis was to develop the understanding of RZ biogeochemical processes so as to provide a sound scientific basis for protection of surface water quality in boreal forests. The work was based on measurements from stream, riparian, and upslope monitoring sites in the 68 km² Krycklan catchment in northern Sweden. Specifically, the study of dissolved organic carbon (DOC), base cations (BC), silicon (Si), and sulfate (SO₄²⁻) was included. Opposite SO₄²⁻ and DOC trends were observed in both stream and riparian water, whereas no trends were apparent in the upslope area. This suggests that RZ processes control stream SO₄²⁻ and DOC independently of upslope soils. On the other hand, the upslope signal of BC and Si was maintained through the RZ and subsequently exported to the streams. RZs were found to have a long-term potential to export DOC from both new and old carbon pools. This, in combination with predicted future climate and exhaustion of residual S pools accumulated during the acidification period, is likely to increase DOC concentrations affecting surface water quality and the global carbon cycle. The hydrological connectivity between RZs and streams can be conceptualized as a ‘dominant source layer’, the narrow depth range with the highest contribution to solute and water fluxes. Local hydromorphology drives spatial heterogeneity in the distribution of RZs and in the intensity of their biogeochemical functions including retention via interaction with organic matter and transformation via redox reactions. Overall, this thesis provides new insights into the role of the RZ in catchment biogeochemistry and proposes a conceptualization of its function and heterogeneity. These outcomes are an essential prerequisite for ecologically sustainable and economically effective land management that preserves surface water quality.
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| 16. |
- Ledesma, Jose, et al.
(författare)
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Boreal forest riparian zones regulate stream sulfate and dissolved organic carbon
- 2016
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 560-561, s. 110-122
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Tidskriftsartikel (refereegranskat)abstract
- In boreal forest catchments, solute transfer to streams is controlled by hydrological and biogeochemical processes occurring in the riparian zone (RZ). However, RZs are spatially heterogeneous and information about solute chemistry is typically limited. This is problematic when making inferences about stream chemistry. Hypothetically, the strength of links between riparian and stream chemistry is time-scale dependent. Using a ten-year (2003-2012) dataset from a northern Swedish catchment, we evaluated the suitability of RZ data to infer stream dynamics at different time scales. We focus on the role of the RZ versus upslope soils in controlling sulfate (SO42-) and dissolved organic carbon (DOC). A priori, declines in acid deposition and redox-mediated SO42- pulses control sulfur (S) fluxes and pool dynamics, which in turn affect dissolved organic carbon (DOC). We found that the catchment is currently a net source of S, presumably due to release of the S pool accumulated during the acidification period. In both, RZ and stream, SO42- concentrations are declining over time, whereas DOC is increasing. No temporal trends in SO42- and DOC were observed in upslope mineral soils. SO42- explained the variation of DOC in stream and RZ, but not in upslope mineral soil. Moreover, as SO42- decreased with time, temporal variability of DOC increased. These observations indicate that: (1) SO42- is still an important driver of DOC trends in boreal catchments and (2) RZ processes control stream SO42- and subsequently DOC independently of upslope soils. These phenomena are likely occurring in many regions recovering from acidification. Because water flows through a heterogeneous mosaic of RZs before entering the stream, upscaling information from limited RZ data to the catchment level is problematic at short-time scales. However, for long-term trends and annual dynamics, the same data can provide reasonable representations of riparian processes and support meaningful inferences about stream chemistry. (C) 2016 The Authors. Published by Elsevier B.V.
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| 17. |
- Ledesma, Jose, et al.
(författare)
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Ecohydrological consequences of tree removal in an urban park evaluated using open data, free software and a minimalist measuring campaign
- 2019
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 655, s. 1495-1504
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Tidskriftsartikel (refereegranskat)abstract
- With ongoing global climate change and an increasingly urbanized population, the importance of city parks and other forms of urban vegetation increases. Trees in urban parks can play an important role in mitigating runoff and delivering other ecosystem services. Park managers, E-NGOs, citizen scientists and others are increasingly called upon to evaluate the possible consequences of changes in park management such as, e.g., tree removal. Here, we present an unorthodox approach to hydrological modelling and its potential use in local policy making regarding urban greenery. The approach consists of a minimalist field campaign to characterize vegetation and soil moisture status combined with a novel model calibration using freely available data and software. During modelling, we were able to obtain coefficients of determination (R-2) of 0.66 and 0.73 for probe-measured and simulated soil moisture under tree stand and park lawn land covers respectively. The results demonstrated that tree cover had a significant positive effect on the hydrological regime of the locality through interception, transpiration and effects on soil moisture. Simulations suggested that tree cover was twice as effective at mitigating runoff than park lawn and almost seven times better than impervious surfaces. In the case of a potential replacement of tree vegetation in favour of park lawn or impervious surfaces an increase in runoff of 14% and 81% respectively could be expected. The main conclusion drawn from our study was that such an approach can be a very useful tool for supporting local decision-making processes as it offers a freely available, cheap and relatively easy-to-use way to describe the hydrological consequences of landcover change (e.g., tree removal) with sufficient accuracy. (C) 2018 The Authors. Published by Elsevier B.V.
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| 18. |
- Ledesma, Jose, et al.
(författare)
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Future changes in the Dominant Source Layer of riparian lateral water fluxes in a subhumid Mediterranean catchment
- 2021
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Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694 .- 1879-2707. ; 595
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Tidskriftsartikel (refereegranskat)abstract
- The 'Dominant Source Layer' (DSL) is defined as the riparian zone (RZ) depth stratum that contributes the most to water and solute fluxes to streams. The concept can be used to explain timing and amount of matter transferred from RZs to streams in forest headwaters. Here, we investigated the potential impact of future climate changes on the long-term position of the DSL in a subhumid Mediterranean headwater catchment. We used the rainfall-runoff model PERSiST to simulate reference (1981-2000) and future (2081-2100) stream runoff. The latter were simulated using synthetic temperature, precipitation, and inter-event length scenarios in order to simulate possible effects of changes in temperature, rainfall amount, and rainfall event frequency and intensity. Simulated stream runoff was then used to estimate RZ groundwater tables and the proportion of lateral water flux at every depth in the riparian profile; and hence the DSL. Our simulations indicated that future changes in temperature and precipitation will have a similar impact on the long-term DSL position. Nearly all scenarios projected that, together with reductions in stream runoff and water exports, the DSL will move down in the future, by as much as ca. 30 cm. Shallow organic-rich layers in the RZ will only be hydrologically activated during sporadic, large rainfall episodes predicted for the most extreme inter-event length scenarios. Consequently, terrestrial organic matter inputs to streams will decrease, likely reducing catchment organic matter exports and stream dissolved organic carbon concentrations. This study highlights the importance of identifying vertical, hydrologically active layers in the RZ for a better understanding of the potential impact of future climate on lateral water transfer and their relationship with surface water quality and carbon cycling.
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| 19. |
- Ledesma, Jose
(författare)
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Future hydrological constraints of the Montseny brook newt (Calotriton arnoldi) under changing climate and vegetation cover
- 2019
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 9, s. 9736-9747
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Tidskriftsartikel (refereegranskat)abstract
- The Montseny brook newt (Calotriton arnoldi) is a critically endangered amphibian species which inhabits a small 20 km(2) holm oak and beech forest area in NE Spain. Calotriton arnoldi strictly lives in running waters and might be highly vulnerable to hydrological perturbations expected to occur under climate and vegetation cover changes. Knowledge about the potential response of the species habitat to environmental changes can help assessing the actions needed for its conservation. Based on knowledge of the species and supported by observations, we proposed daily low and high streamflow event thresholds for the viability of C. arnoldi. We used the rainfall-runoff model PERSiST to simulate changes in the frequency and duration of these events, which were predicted under two climate and four vegetation cover scenarios for near-future (2031-2050) and far-future (2081-2100) periods in a reference catchment. All future scenarios projected a significant decrease in annual streamflow (from 21% to as much as 67%) with respect to the reference period. The frequency and length of low streamflow events will dramatically increase. In contrast, the risk of catastrophic drift linked to high streamflow events was predicted to decrease. The potential change in vegetation toward an expansion of holm oak forests will be more important than climate changes in determining threshold low flow conditions. We thus demonstrated that consideration of potential changes in vegetation and not only changes in climate variables is essential in simulating future streamflows. This study shows that future low streamflow conditions will pose a severe threat for the survival of C. arnoldi and may help taking management actions, including limiting the expansion of holm oak forest, for ameliorating the species habitat and help its conservation.
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| 20. |
- Ledesma, Jose, et al.
(författare)
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Gridded climate data products are an alternative to instrumental measurements as inputs to rainfall–runoff models
- 2017
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Ingår i: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 31, s. 3283-3293
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Tidskriftsartikel (refereegranskat)abstract
- Rainfall-runoff models are widely used to predict flows using observed (instrumental) time series of air temperature and precipitation as inputs. Poor model performance is often associated with difficulties in estimating catchment-scale meteorological variables from point observations. Readily available gridded climate products are an underutilized source of temperature and precipitation time series for rainfall-runoff modelling, which may overcome some of the performance issues associated with poor-quality instrumental data in small headwater monitoring catchments. Here we compare the performance of instrumental measured and E-OBS gridded temperature and precipitation time series as inputs in the rainfall-runoff models "PERSiST" and "HBV" for flow prediction in six small Swedish catchments. For both models and most catchments, the gridded data produced statistically better simulations than did those obtained using instrumental measurements. Despite the high correspondence between instrumental and gridded temperature, both temperature and precipitation were responsible for the difference. We conclude that (a) gridded climate products such as the E-OBS dataset could be more widely used as alternative input to rainfall-runoff models, even when instrumental measurements are available, and (b) the processing applied to gridded climate products appears to provide a more realistic approximation of small catchment-scale temperature and precipitation patterns needed for flow simulations. Further research on this issue is needed and encouraged.
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| 21. |
- Ledesma, Jose
(författare)
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Increased Dissolved Organic Carbon Concentrations in Peat-Fed UK Water Supplies Under Future Climate and Sulfate Deposition Scenarios
- 2020
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Ingår i: Water Resources Research. - 0043-1397 .- 1944-7973. ; 56
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Tidskriftsartikel (refereegranskat)abstract
- Peatlands are globally-important terrestrial carbon stores as well as regional sources of potable water supply. Water draining from peatlands is rich in dissolved organic carbon (DOC), which can be problematic for water treatment. However, it is unclear how future climate and sulfate deposition changes may impact DOC in peatland-derived potable water. The United Kingdom (UK) is a global hotspot that consumes 79% of all potable water derived directly from peatlands. Here, a physically-based hydrological model and a biogeochemical organic carbon model were used to predict discharge and DOC concentration in nine hotspots of peatland-derived potable water use in the UK under a range of 21st century climate and sulfate deposition scenarios. These nine catchments supply 72% of all peatland-derived water consumed in the UK and 57% of the global total, equivalent to the total domestic consumption of over 14 million people. Our simulations indicate that annual discharges will decrease and that mean annual DOC concentrations will increase under all future scenarios (by as much as 53.4% annually for the highest emissions scenario) in all catchments. Large increases (by as much as a factor of 1.6) in DOC concentration in the 2090s over the baseline period are projected for autumn and winter, seasons when DOC concentrations are already high in the baseline datasets such that water treatment works often reach their capacity to cope. The total DOC flux is largely insensitive to future climate change because the projected increase in DOC concentration is mostly counterbalanced by the projected decrease in discharge.
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| 22. |
- Ledesma, Jose
(författare)
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Long-Term Climatic and Anthropogenic Impacts on Streamwater Salinity in New York State: INCA Simulations Offer Cautious Optimism
- 2018
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 52, s. 1339-1347
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Tidskriftsartikel (refereegranskat)abstract
- The long-term application of road salts has led to a rise in surface water chloride (Cl-) concentrations. While models have been used to assess the potential future impacts of continued deicing practices, prior approaches have not incorporated changes in climate that are projected to impact hydrogeology in the 21st century. We use an INtegrated CAtchment (INCA) model to simulate Cl- concentrations in the Tioughnioga River watershed. The model was run over a baseline period (1961-1990) and climate simulations from a range of GCMs run over three 30-year intervals (2010-2039; 2040-2069; 2070-2099). Model projections suggest that Cl- concentrations in the two river branches will continue to rise for several decades, before beginning to decline around 2040-2069, with all GCM scenarios indicating and associated salt applications over the 21st century. The delay in stream response is most likely attributed to climate change and continued contribution of Cl- from aquifers. By 2100, surface water Cl- concentrations will decrease to below 1960s values. Catchments dominated by urban lands will experience a decrease in average surface water Cl-, although moderate compared to more rural catchments.
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| 23. |
- Ledesma, Jose, et al.
(författare)
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Long-term dynamics of dissolved organic carbon: Implications for drinking water supply
- 2012
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 432, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- Surface waters are the main source of drinking water in many regions. Increasing organic carbon concentrations are a cause for concern in Nordic countries since both dissolved and particulate organic carbon can transport contaminants and adversely affect drinking water treatment processes. We present a long-term study of dynamics of total (particulate and dissolved) organic carbon (TOC) concentrations in the River Fyris. This river supplies drinking water to approximately 200000 people in Uppsala, Sweden. The River Fyris is a main tributary to Lake Malaren, which supplies drinking water to approximately 2 million people in the greater Stockholm area. Utilities responsible for drinking water supply in both Uppsala and Stockholm have expressed concerns about possible increases in TOC. We evaluate organic carbon dynamics within the Fyris catchment by calculating areal mass exports using observed TOC concentrations and modeled flows and by modeling dissolved organic carbon (as a proxy for TOC) using the dynamic, process based INCA-C model. Exports of TOC from the catchment ranged from 0.8 to 5.8 g m(-2) year(-1) in the period 1995-2010. The variation in annual exports was related to climatic variability which influenced seasonality and amount of runoff. Exports and discharge uncoupled at the end of 2008. A dramatic increase in TOC concentrations was observed in 2009, which gradually declined in 2010-2011. INCA-C successfully reproduced the intra- and inter-annual variation in concentrations during 1996-2008 and 2010-2011 but failed to capture the anomalous increase in 2009. We evaluated a number of hypotheses to explain the anomaly in 2009 TOC values, ultimately none proved satisfactory. We draw two main conclusions: there is at least one unknown or unmeasured process controlling or influencing surface water TOC and INCA-C can be used as part of the decision-making process for current and future use of rivers for drinking water supply. (C) 2012 Elsevier B.V. All rights reserved.
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| 24. |
- Ledesma, Jose, et al.
(författare)
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Minimal climate change impacts on natural organic matter forecasted for a potable water supply in Ireland
- 2018
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 630, s. 869-877
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Tidskriftsartikel (refereegranskat)abstract
- Natural organic matter poses an increasing challenge to water managers because of its potential adverse impacts on water treatment and distribution, and subsequently human health. Projections were made of impacts of climate change on dissolved organic carbon (DOC) in the primarily agricultural Boyne catchment which is used as a potable water supply in Ireland. The results indicated that excluding a potential rise in extreme precipitation, future projected loads are not dissimilar to those observed under current conditions This is because projected increases in DOC concentrations are offset by corresponding decreases in precipitation and hence river flow. However, the results presented assume no changes in land use and highlight the predicted increase in DOC loads from abstracted waters at water treatment plants. (C) 2018 Published by Elsevier B.V.
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| 25. |
- Ledesma, Jose
(författare)
-
Modelling the effects of climate and land-use change on the hydrochemistry and ecology of the River Wye (Wales)
- 2018
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 627, s. 733-743
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Tidskriftsartikel (refereegranskat)abstract
- Interactions between climate change and land use change might have substantial effects on aquatic ecosystems, but are still poorly understood. Using theWelsh RiverWye as a case study, we linked models of water quality (Integrated Catchment - INCA) and climate (GFDL - Geophysical Fluid Dynamics Laboratory and IPSL - Institut Pierre Simon Laplace) under greenhouse gas scenarios (RCP4.5 and RCP8.5) to drive a bespoke ecosystem model that simulated the responses of aquatic organisms. The potential effects of economic and social development were also investigated using scenarios fromthe EUMARS project (Managing Aquatic Ecosystems andWater Resources under Multiple Stress). Longitudinal position along the river mediated response to increasing anthropogenic pressures. Upland locations appeared particularly sensitive to nutrient enrichment or potential re-acidification compared to lowland environments which are already eutrophic. These results can guide attempts to mitigate future impacts and reiterate the need for sensitive land management in upland, temperate environments which are likely to become increasingly important to water supply and biodiversity conservation as the effects of climate change intensify. (C) 2018 Elsevier B.V. All rights reserved.
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| 26. |
- Ledesma, Jose, et al.
(författare)
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Potential for long-term transfer of dissolved organic carbon from riparian zones to streams in boreal catchments
- 2015
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 21, s. 2963-2979
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Tidskriftsartikel (refereegranskat)abstract
- Boreal regions store most of the global terrestrial carbon, which can be transferred as dissolved organic carbon (DOC) to inland waters with implications for both aquatic ecology and carbon budgets. Headwater riparian zones (RZ) are important sources of DOC, and often just a narrow ‘dominant source layer' (DSL) within the riparian profile is responsible for most of the DOC export. Two important questions arise: how long boreal RZ could sustain lateral DOC fluxes as the sole source of exported carbon and how its hydromorphological variability influences this role. We estimate theoretical turnover times by comparing carbon pools and lateral exports in the DSL of 13 riparian profiles distributed over a 69km2 catchment in northern Sweden. The thickness of the DSL was 36±18 (average ± SD) cm. Thus, only about one-third of the 1-m-deep riparian profile contributed 90% of the lateral DOC flux. The 13 RZ exported 8.7±6.5g C m-2year-1, covering the whole range of boreal stream DOC exports. The variation could be explained by local hydromorphological characteristics including RZ width (R2=0.90). The estimated theoretical turnover times were hundreds to a few thousands of years, that is there is a potential long-lasting supply of DOC. Estimates of net ecosystem production in the RZ suggest that lateral fluxes, including both organic and inorganic C, could be maintained without drawing down the riparian pools. This was supported by measurements of stream DO14C that indicated modern carbon as the predominant fraction exported, including streams disturbed by ditching. The transfer of DOC into boreal inland waters from new and old carbon sources has a major influence on surface water quality and global carbon balances. This study highlights the importance of local variations in RZ hydromorphology and DSL extent for future DOC fluxes under a changing climate.
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| 27. |
- Ledesma, Jose, et al.
(författare)
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Riparian zone control on base cation concentration in boreal streams
- 2013
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 10:6, s. 3849-3868
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Tidskriftsartikel (refereegranskat)abstract
- Riparian zones (RZ) are a major factor controlling water chemistry in forest streams. Base cations' (BC) concentrations, fluxes, and cycling in the RZ merit attention because a changing climate and increased forest harvesting could have negative consequences, including re-acidification, for boreal surface waters. We present a two-year study of BC and silica (Si) flow-weighted concentrations from 13 RZ and 14 streams in different landscape elements of a boreal catchment in northern Sweden. The spatial variation in BC and Si dynamics in both RZ and streams was explained by differences in landscape element type, with highest concentrations in silty sediments and lowest concentrations in peat-dominated wetland areas. Temporal stability in BC and Si concentrations in riparian soil water, remarkably stable Mg/Ca ratios, and homogeneous mineralogy suggest that patterns found in the RZ are a result of a distinct mineralogical upslope signal in groundwater. Stream water Mg/Ca ratios indicate that the signal is subsequently maintained in the streams. Flow-weighted concentrations of Ca, Mg, and Na in headwater streams were represented by the corresponding concentrations in the RZ, which were estimated using the Riparian Flow-Concentration Integration Model (RIM) approach. Stream and RZ flow-weighted concentrations differed for K and Si, suggesting a stronger biogeochemical influence on these elements, including K recirculation by vegetation and retention of Si within the RZ. Potential increases in groundwater levels linked to forest harvesting or changes in precipitation regimes would tend to reduce BC concentrations from RZ to streams, potentially leading to episodic acidification.
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| 28. |
- Ledesma, Jose, et al.
(författare)
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Stream Dissolved Organic Matter Composition Reflects the Riparian Zone, Not Upslope Soils in Boreal Forest Headwaters
- 2018
-
Ingår i: Water resources research. - 0043-1397 .- 1944-7973. ; 54:6, s. 3896-3912
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Tidskriftsartikel (refereegranskat)abstract
- Despite the strong quantitative evidence that riparian zones (RZs) are the dominant source of dissolved organic carbon (DOC) to boreal streams, there is still a debate about the potential contribution of upslope areas to fluvial carbon export. To shed new light into this debate, we investigated the molecular composition of dissolved organic matter (DOM) in four upslope-riparian-stream transects in a Northern Swedish forest catchment using absorbance (A(254)/A(365) and SUVA(254)) and fluorescence (fluorescence and freshness indices) metrics. Based on these metrics, our results indicate that stream water DOM molecular composition resembles that of RZs and significantly differs from that of upslope areas. The resemblance between stream and riparian DOM was most apparent for the Dominant Source Layer (DSL), a narrow RZ stratum that, theoretically, contributes the most to solute and water fluxes to streams. Spectroscopic characterization based on traditional interpretations of the metrics suggested that mineral upslope (podzol) DOM is less aromatic, more microbially derived, and more recently produced than organic riparian (histosol) and stream DOM. We conclude that RZs, and specifically DSLs, are the main sources of DOC to boreal headwater streams and potentially to other streams located in low-gradient, organic matter-rich catchments. Plain Language Summary Understanding carbon cycling in natural ecosystems is critical because ongoing climate change can promote the release of previously stored carbon in forest soils to streams and rivers, with the potential to form carbon dioxide, the main greenhouse gas. This is particularly important in boreal ecosystems, which are the largest stores of terrestrial carbon in the world. In this study, we identify the near-stream area, the so-called riparian zone, as the main source of carbon from boreal forest soils to streams. We provide qualitative data to support this, which together with previous quantitative analyses, make up enough evidence to support that the riparian zone is the main source of carbon to streams. As there is still a debate about the potential contribution of other areas in the ecosystem to the fluvial carbon export, our study importantly highlights that the riparian zone should be the focus of scientific assessments and management strategies in relation to carbon exports in surface waters.
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| 29. |
- Ledesma, Jose
(författare)
-
The history of rainfall data time-resolution in a wide variety of geographical areas
- 2020
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Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694 .- 1879-2707. ; 590
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Tidskriftsartikel (refereegranskat)abstract
- Collected rainfall records by gauges lead to key forcings in most hydrological studies. Depending on sensor type and recording systems, such data are characterized by different time-resolutions (or temporal aggregations), t(a). We present an historical analysis of the time-evolution of t(a) based on a large database of rain gauge networks operative in many study areas. Globally, t(a) data were collected for 25,423 rain gauge stations across 32 geographic areas, with larger contributions from Australia, USA, Italy and Spain. For very old networks early recordings were manual with coarse time-resolution, typically daily or sometimes monthly. With a few exceptions, mechanical recordings on paper rolls began in the first half of the 20th century, typically with t(a) of 1 h or 30 min. Digital registrations started only during the last three decades of the 20th century. This short period limits investigations that require long time-series of sub-daily rainfall data, e.g, analyses of the effects of climate change on short-duration (sub-hourly) heavy rainfall. In addition, in the areas with rainfall data characterized for many years by coarse time-resolutions, annual maximum rainfall depths of short duration can be potentially underestimated and their use would produce errors in the results of successive applications. Currently, only 50% of the stations provide useful data at any time-resolution, that practically means t(a) = 1 min. However, a significant reduction of these issues can be obtained through the information content of the present database. Finally, we suggest an integration of the database by including additional rain gauge networks to enhance its usefulness particularly in a comparative analysis of the effects of climate change on extreme rainfalls of short duration available in different locations.
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| 30. |
- Ledesma, Jose, et al.
(författare)
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Towards an Improved Conceptualization of Riparian Zones in Boreal Forest Headwaters
- 2018
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Ingår i: Ecosystems (New York. Print). - : Springer. - 1432-9840 .- 1435-0629. ; 21:2, s. 297-315
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Tidskriftsartikel (refereegranskat)abstract
- The boreal ecoregion supports about one-third of the world's forest. Over 90% of boreal forest streams are found in headwaters, where terrestrial-aquatic interfaces are dominated by organic matter (OM)-rich riparian zones (RZs). Because these transition zones are key features controlling catchment biogeochemistry, appropriate RZ conceptualizations are needed to sustainably manage surface water quality in the face of a changing climate and increased demands for forest biomass. Here we present a simple, yet comprehensive, conceptualization of RZ function based on hydrological connectivity, biogeochemical processes, and spatial heterogeneity. We consider four dimensions of hydrological connectivity: (1) laterally along hillslopes, (2) longitudinally along the stream, (3) vertically down the riparian profile, and (4) temporally through event-based and seasonal changes in hydrology. Of particular importance is the vertical dimension, characterized by a 'Dominant Source Layer' that has the highest contribution to solute and water fluxes to streams. In addition to serving as the primary source of OM to boreal streams, RZs shape water chemistry through two sets of OM-dependent biogeochemical processes: (1) transport and retention of OM-associated material and (2) redox-mediated transformations controlled by RZ water residence time and availability of labile OM. These processes can lead to both retention and release of pollutants. Variations in width, hydrological connectivity, and OM storage drive spatial heterogeneity in RZ biogeochemical function. This conceptualization provides a useful theoretical framework for environmental scientists and ecologically sustainable and economically effective forest management in the boreal region and elsewhere, where forest headwaters are dominated by low-gradient, OM-rich RZs.
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| 31. |
- Lupon, Anna, et al.
(författare)
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Riparian evapotranspiration is essential to simulate streamflow dynamics and water budgets in a Mediterranean catchment
- 2018
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Ingår i: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 22, s. 4033-4045
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Tidskriftsartikel (refereegranskat)abstract
- Riparian trees can regulate streamflow dynamics and water budgets by taking up large amounts of water from both soil and groundwater compartments. However, their role has not been fully recognized in the hydrologic literature and the catchment modeling community. In this study, we explored the influence of riparian evapotranspiration (ET) on streamflow by simulating daily stream water exports from three nested Mediterranean catchments, both including and excluding the riparian compartment in the structure of the PERSiST (Precipitation, Evapotranspiration and Runoff Simulator for Solute Transport) rainfall-runoff model. The model goodness of fit for the calibration period (September 2010-August 2012) significantly improved with the inclusion of the riparian compartment, especially during the vegetative period, when according to our simulations, the riparian zone significantly reduced the overestimation of mean daily streamflow (from 53 % to 27 %). At the catchment scale, simulated riparian ET accounted for 5.5 % to 8.4 % of annual water depletions over a 20-year reference period (1981-2000), and its contribution was especially noticeable during summer (from 8 % to 26 %). Simulations considering climate change scenarios suggest large increases in riparian ET during the dormant period (from 19 % to 46 %) but only small increases (from 1 % to 2 %) in its contribution to annual water budgets. Overall, our results highlight that a good assessment of riparian ET is essential for understanding catchment hydrology and streamflow dynamics in Mediterranean regions. Thus, the inclusion of the riparian compartment in hydrological models is strongly recommended in order to establish proper management strategies in water-limited regions.
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| 32. |
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| 33. |
- Oni, Stephen, et al.
(författare)
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Local- and landscape-scale impacts of clear-cuts and climate change on surface water dissolved organic carbon in boreal forests
- 2015
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Ingår i: Journal of Geophysical Research - Biogeosciences. - 2169-8953 .- 2169-8961. ; 120:11, s. 2402-2426
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Tidskriftsartikel (refereegranskat)abstract
- Forest harvesting and climate change may significantly increase concentrations and fluxes of dissolved organic carbon (DOC) in boreal surface waters. However, the likely magnitude of any effect will vary depending on the landscape-element type and spatial scale. We used a chain of hydrological, empirical, and process-based biogeochemical models coupled to an ensemble of downscaled Regional Climate Model experiments to develop scenario storylines for local- and landscape-scale effects of forest harvesting and climate change on surface water DOC concentrations and fluxes. Local-scale runoff, soil temperature, and DOC dynamics were simulated for a range of forest and wetland landscape-element types and at the larger landscape scale. The results indicated that climate change will likely lead to greater winter flows and earlier, smaller spring peaks. Both forest harvesting and climate change scenarios resulted in large increases in summer and autumn runoff and higher DOC fluxes. Forest harvesting effects were clearly apparent at local scales. While at the landscape scale, approximately 1 mg L−1 (or 10%) of the DOC in surface waters can be attributed to clear-cuts, both climate change and intensified forestry can each increase DOC concentrations by another 1 mg L−1 in the future, which is less than that seen in many waterbodies recovering from acidification. These effects of forestry and climate change on surface water DOC concentrations are additive at a landscape scale but not at the local scale, where a range of landscape-element specific responses were observed.
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| 34. |
- Oni, Stephen, et al.
(författare)
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Using dry and wet year hydroclimatic extremes to guide future hydrologic projections
- 2016
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Ingår i: Hydrology and Earth System Sciences. - : Copernicus GmbH. - 1027-5606 .- 1607-7938. ; 20, s. 2811-2825
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Tidskriftsartikel (refereegranskat)abstract
- There are growing numbers of studies on climate change impacts on forest hydrology, but limited attempts have been made to use current hydroclimatic variabilities to constrain projections of future climatic conditions. Here we used historical wet and dry years as a proxy for expected future extreme conditions in a boreal catchment. We showed that runoff could be underestimated by at least 35% when dry year parameterizations were used for wet year conditions. Uncertainty analysis showed that behavioural parameter sets from wet and dry years separated mainly on precipitation-related parameters and to a lesser extent on parameters related to landscape processes, while uncertainties inherent in climate models (as opposed to differences in calibration or performance metrics) appeared to drive the overall uncertainty in runoff projections under dry and wet hydroclimatic conditions. Hydrologic model calibration for climate impact studies could be based on years that closely approximate anticipated conditions to better constrain uncertainty in projecting extreme conditions in boreal and temperate regions.
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| 35. |
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| 36. |
- Abbafati, Cristiana, et al.
(författare)
-
- 2020
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Tidskriftsartikel (refereegranskat)
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