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Sökning: LAR1:umu > Umeå universitet

  • Resultat 41421-41430 av 88501
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41421.
  • Klaminder, Jonatan, et al. (författare)
  • Drug-Induced Behavioral Changes : Using Laboratory Observations to Predict Field Observations
  • 2016
  • Ingår i: Frontiers in Environmental Science. - Lausanne, Schweiz : Frontiers Media SA. - 2296-665X. ; 4
  • Tidskriftsartikel (refereegranskat)abstract
    • Behavioral assays constitute important research tools when assessing how fish respond to environmental change. However, it is unclear how behavioral modifications recorded in laboratory assays are expressed in natural ecosystems, a limitation that makes it difficult to evaluate the predictive power of laboratory-based measurements. In this study, we hypothesized that exposure to a benzodiazepine (i.e., oxazepam) increases boldness and activity in laboratory assays as well as in field assays – that is, laboratory results can be used to predict field results. Moreover, we expected the modified behavior to affect other important ecological measures such as habitat selection and home range. To test our hypothesis, we exposed European perch (Perca fluviatilis) to oxazepam and measured subsequent changes in behavioral trials both in laboratory assays and in a lake ecosystem populated with a predatory fish species, pike (Esox lucius). In the lake, the positions of both perch and pike were tracked every three minutes for a month using acoustic telemetry. In the laboratory assay, the oxazepam-exposed perch were bolder and more active than the non-exposed perch. In the lake assay, the oxazepam-exposed perch were also more bold and active, had a larger home range, and used pelagic habitats more than the non-exposed perch. We conclude that ecotoxicological behavioral assays are useful for predicting the effects of exposure in natural systems. However, although individual responses to exposure were similar in both the laboratory and field trials, effects were more obvious in the field study, mainly due to reduced variability in the behavior measures from the lake. Hence, short-term behavioral assays may fail to detect all the effects expressed in natural environments. Nevertheless, our study clearly demonstrates that behavior modifications observed in laboratory settings can be used to predict how fish perform in aquatic ecosystems. 
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41422.
  • Klaminder, Jonatan, et al. (författare)
  • Estimating the mean residence time of lead in the organic horizon of boreal forest soils using 210-lead, stable lead and a soil chronosequence
  • 2006
  • Ingår i: Biogeochemistry. - : Springer Netherlands. - 0168-2563 .- 1573-515X. ; 78:1, s. 31-49
  • Tidskriftsartikel (refereegranskat)abstract
    • Knowledge about the residence time of lead in the organic horizon (mor layer; O-horizon) overlaying forest mineral soils is important for the prediction of past and future lead levels in the boreal environment. To estimate the mean residence time (MRT) of lead in the mor layer, we use in this study from Northern Sweden three different approaches: (1) lead-210 is applied as a tracer of lead migration; (2) estimations of loss rates of stable lead (concentrations and 206Pb/207Pb ratios) from the mor layer at an undisturbed forest setting, and (3) a study of lead in a soil series with sites of different age (a chronosequence of 20–220 years). In the last two approaches we compared measured inventories in the soil with estimated inventories derived using analyses of lake sediments. The results suggested a MRT of about 250 years in the mor layer in the mature forest and in the older parts of the chronosequence it was at least >170 years. The agreement between the three different approaches gives good credibility to this estimate. It is also supported by a modeling of trends in the 206Pb/207Pb ratio both between single cores and with depth in the mor layer. Our results suggest that it will take centuries for the deeper parts of the mor layer of undisturbed boreal forest soils to fully respond to decreased atmospheric lead pollution. However, data from the chronosequence indicate that the response could be much faster (MRT<50 years) in the mor layer at early stages of forest succession where graminoid and broadleaved litter fall dominates over conifer litter.
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41423.
  • Klaminder, Jonatan, et al. (författare)
  • Flux rates of atmospheric lead pollution within soils of a small catchment in northern Sweden and their implications for future stream water quality
  • 2006
  • Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 40:15, s. 4639-45
  • Tidskriftsartikel (refereegranskat)abstract
    • It is not well-known how the accumulated pool of atmospheric lead pollution in the boreal forest soil will affect the groundwater and surface water chemistry in the future as this lead migrates through the soil profile. This study uses stable lead isotopes (206Pb/207Pb and 208Pb/ 207Pb ratios) to trace the transport of atmospheric lead pollution within the soil of a small catchment and predict future lead level changes in a stream draining the catchment. Low 206Pb/207Pb and 208Pb/207Pb ratios for the lead in the soil water (1.16 ± 0.02; 2.43 ± 0.03) and streamwater (1.18 ± 0.03; 2.42 ± 0.03) in comparison to that of the mineral soil (>1.4; >2.5) suggest that atmospheric pollution contributes by about 90% (65−100%) to the lead pool found in these matrixes. Calculated transport rates of atmospheric lead along a soil transect indicate that the mean residence time of lead in organic and mineral soil layers is at a centennial to millennial time scale. A maximum release of the present pool of lead pollution in the soil to the stream is predicted to occur within 200−800 years. Even though the uncertainty of the prediction is large, it emphasizes the magnitude of the time lag between the accumulation of atmospheric lead pollution in soils and the subsequent response in streamwater quality.
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41424.
  • Klaminder, Jonatan, 1976-, et al. (författare)
  • Holes in the tundra : Invasive earthworms alter soil structure and moisture in tundra soils
  • 2023
  • Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 859
  • Tidskriftsartikel (refereegranskat)abstract
    • Human introductions have resulted in earthworms establishing in the Arctic, species known to cause cascading ecosystem change. However, few quantitative outdoor experiments have been performed that describe how these soil modifying earthworms are reshaping structures in tundra soils. In this study, we used three-dimensional (3-D) X-ray images of soil cores (approximately 10 cm diameter, 20 cm height, N = 48) to assess how earthworms (Aporrectodea sp. and Lumbricus sp.) affect soil structure and macropore networks in an outdoor mesocosm experiment that lasted four summers. Effects were assessed in both shrub-dominated (heath) and herb-dominated (meadow) tundra. Earthworms almost doubled the macroporosity in meadow soils and tripled macroporosity in heath. Interestingly, the fractal dimension of macropores decreased in response to earthworm burrowing in both systems, indicating that the presence of earthworms reduced the geometric complexity in comparison to other pore-generating processes active in the tundra. Observed effects on soil structure occurred along with a dramatically reduced soil moisture content, which was observed the first winter after earthworm introduction in the meadow. Our findings suggest that predictions of future changes in vegetation and soil carbon pools in the Arctic should include major impacts on soil properties that earthworms induce.
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41425.
  • Klaminder, Jonatan, et al. (författare)
  • Is there a chronological record of atmospheric mercury and lead deposition preserved in the mor layer (O-horizon) of boreal forest soils
  • 2008
  • Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier BV. - 0016-7037 .- 1872-9533. ; 72, s. 703-712
  • Tidskriftsartikel (refereegranskat)abstract
    • The organic horizon (the mor layer) of podzolized boreal forest soils has accumulated atmospheric fallout of mercury and lead over centuries, resulting in current concentrations close to levels where negative effects on soil biota are thought to occur. To what extent the pollution history is preserved in the stratigraphy of this horizon is not well known. In this study we asses whether the chronology of a large historic pulse of atmospheric pollution emitted from the Ronnskar smelter in northern Sweden, particularly between 1950 and 1980, is preserved within the stratigraphy of the mor layer, which is typically 5-cm thick. Vertical sub-sampling (<= 5 mm) of five mor profiles sampled along a 100-km pollution gradient away from the smelter are analyzed for mercury and lead concentrations, spheroidal carbonaceous particles from fossil fuel combustion (SCPs) and stable lead isotopes (Pb-206/Pb-207 and Pb-208/Pb-207). Their vertical distribution is compared with the temporal variations in atmospheric inputs reconstructed for the last similar to 100 years from analyses of an ombrotrophic peat core and a varved take sediment core sampled within a distance of 50 km of the smelter. The mor profiles situated <= 12 km from the smelter record the pollution history of the smelter. There is a 20 to 40-times enrichment of Hg, Pb and SCP at the transition in the O-horizon from the F- to H-layer compared to the basal part and a distinct peak in the Pb-206/Pb-207 ratio (similar to 1.22) in the F-layer. The mor profiles situated outside the historical contamination range of the smelter (80 and 100 km away) record no obvious influence from the Ronnskar smelter, instead their vertical Pb-206/Pb-207 profiles follow the general regional pollution history in northern Sweden. We conclude that the mor layer preserves a record of atmospheric Hg, Pb and SCP inputs and due to low leaching rates this organic horizon serves as a semi-archive of atmospheric Hg and Pb pollution. We stress the need of including this property in the existing 'black-box' models predicting the fate of Hg and Pb within contaminated boreal forest soils.
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41426.
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41427.
  • Klaminder, Jonatan, 1976-, et al. (författare)
  • Landscape of ice and fire : uniquely well-preserved scots pine trunks reveal forest fires near the retreating weichselian ice margin
  • 2024
  • Ingår i: Vegetation History and Archaeobotany. - : Springer. - 0939-6314 .- 1617-6278. ; 33, s. 519-527
  • Tidskriftsartikel (refereegranskat)abstract
    • Environmental conditions for trees that established in central Fennoscandia shortly after the final retreat of the Weichselian ice sheet remain poorly understood. In this study we examine tree rings of five well-preserved Pinus sylvestris (Scots pines) that grew in the area in front of the retreating ice sheet in northern Sweden. They became buried in flood sediments deposited by a glacial outburst flood (jökulhlaup) about 9.5–9.9 kyr cal bp and the aim of our study was to search for information regarding damage from fires and bioclimatic conditions in their ancient tree ring records. Our analysis, providing a glimpse into the local early Holocene environment in north-central Sweden, suggests that: 1, there were repeated fires (four fire events detected) during the early Holocene; and 2, bioclimatic conditions when the ancient pines were growing resembled those of modern sub-alpine pine woods. The latter is indicated by their patterns of tree ring growth (growth rate and variation), which were statistically similar to those of pines growing in sub-alpine woods with an open canopy, but different from pines in protected and managed boreal forests. Lower δ13C for the ancient latewood in comparison to pine wood from trees growing near the Scandinavian mountains before the 1850s were probably caused both by stomata fractionation due to lower atmospheric CO2 during the early Holocene and by the moist local environment created by the nearby ancient Ancylus lake, which preceded the Baltic Sea. Periods with cloudy and cold summers were also indicated by the occurrence of ‘false rings’. Finds of charred fragments of Calluna vulgaris (heather, ling), an understory shrub that can burn even with a relatively high moisture content, suggest that heath vegetation was crucial to make fire a reoccurring ecological factor in the area during the early Holocene.
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41428.
  • Klaminder, Jonatan, et al. (författare)
  • Lead Contamination of Subarctic Lakes and Its Response to Reduced Atmospheric Fallout : Can the Recovery Process Be Counteracted by the Ongoing Climate Change?
  • 2010
  • Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 44:7, s. 2335-2340
  • Tidskriftsartikel (refereegranskat)abstract
    • Can a climate-triggered export of old contaminants from the soil alter the lead (Pb) contaminant burden of subarctic lakes? To address this question, we reconstructed the pollution history of three high latitude lakes situated in a region where a recent climatic shift has occurred. Dated sediment records were used as archives of past Pb inputs to the lakes, where the difference in the Pb-206/Pb-207 ratio between atmospheric contaminants (Pb-206/Pb-207 ratio <1.16) and geogenic Pb in the catchment soil (Pb-206/Pb-207 ratio >1.22) were used to trace fluxes of Pb contaminants. Lead contaminants were found in sediments deposited since Roman times. A significant export of Pb from the soil contaminant pool is indicated in two of the lakes surrounded by near-shore permafrost soils. Here, levels of Pb contaminants and Pb-206/Pb-207 ratios of sediments deposited after the 1970s appear not to have been strongly affected by the >= 90% reduction in atmospheric deposition rates and increasing Pb-206/Pb-207 ratios of atmospheric Pb since the 1990s. We concluded that soil processes stimulated by the ongoing climate change at high latitudes might work counteractive to efforts to reduce contaminant levels in subarctic lakes.
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41429.
  • Klaminder, Jonatan, 1976-, et al. (författare)
  • Less anxious salmon smolt become easy prey during downstream migration
  • 2019
  • Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 687, s. 488-493
  • Tidskriftsartikel (refereegranskat)abstract
    • Hatchery-reared salmon smolt used for supplementary stocking often display poor migration behavior compared to wild smolt, which reduces the success of this management action. Oxazepam, an anxiolytic drug, has been shown to intensify salmon smolt migration in mesocosm experiments, and treatment with this drug has, therefore, been suggested as a management option to improve downstream smolt migration. In this study, we tested this by assessing migration performance of hatchery-reared Atlantic salmon (Salmo salar) smolt along a 21-km long natural river-to-sea migration route in a boreal river in Northern Sweden. Using acoustic telemetry, the migration rate and survival of smolt that had been exposed to oxazepam (200 mu g L-1, N = 20) was monitored and compared with a control group (N = 20) of unexposed smolt. Exposed smolt took significantly longer time to initiate migration after release compared to the control fish, but after that we observed no significant difference in downstream migration speed. However, exposed smolt had considerably higher probability of being predated on compared to control smolt. We attribute these results to increased risk-taking and higher activity in oxazepam-exposed smolt, which in turn increased initial non-directional exploratory behavior and decreased predator vigilance. These results are discussed based on current concerns for ecological implications of behavioral modifications induced by pharmaceutical pollution and climate change. We conclude that exposure to oxazepam is an unsuitable management option to prime migration of reared salmon in natural systems.
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41430.
  • Klaminder, Jonatan, et al. (författare)
  • Long-Term Persistence of an Anxiolytic Drug (Oxazepam) in a Large Freshwater Lake
  • 2015
  • Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 49:17, s. 10406-10412
  • Tidskriftsartikel (refereegranskat)abstract
    • Production and human consumption of pharmaceuticals result in contamination of surface waters worldwide. Little is known about the long-term (i.e., over decades) fate of pharmaceuticals in aquatic systems. Here, we show that the most prescribed anxiolytic in Sweden (oxazepam) persists in its therapeutic form for several decades after being deposited in a large freshwater lake. By comparing sediment cores collected in 1995 and 2013, we demonstrate that oxazepam inputs from the early 1970s remained in the sediments until sampling in 2013, despite in situ degradation processes and sediment diagenesis. In laboratory and pond experiments, we further reveal that therapeutic forms of oxazepam can persist over several months in cold (5 degrees C) lake water free from UV light. We conclude that oxazepam can persist in lakes over a time scale much longer than previously realized and that levels can build up in lakes due to both a legacy of past inputs and a growing urban population.
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