| 1. |
- Bergkvist, Bo, et al.
(författare)
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Pools and fluxes of carbon in three Norway spruce ecosystems along a climatic gradient in Sweden
- 2008
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Ingår i: Biogeochemistry. - : Springer Science and Business Media LLC. - 0168-2563 .- 1573-515X. ; 89:1, s. 7-25
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an integrated analysis of organic carbon (C) pools in soils and vegetation, within-ecosystem fluxes and net ecosystem exchange (NEE) in three 40-year old Norway spruce stands along a north-south climatic gradient in Sweden, measured 2001-2004. A process-orientated ecosystem model (CoupModel), previously parameterised on a regional dataset, was used for the analysis. Pools of soil organic carbon (SOC) and tree growth rates were highest at the southernmost site (1.6 and 2.0-fold, respectively). Tree litter production (litterfall and root litter) was also highest in the south, with about half coming from fine roots (< 1 mm) at all sites. However, when the litter input from the forest floor vegetation was included, the difference in total litter input rate between the sites almost disappeared (190-233 g C m(-2) year(-1)). We propose that a higher N deposition and N availability in the south result in a slower turnover of soil organic matter than in the north. This effect seems to overshadow the effect of temperature. At the southern site, 19% of the total litter input to the O horizon was leached to the mineral soil as dissolved organic carbon, while at the two northern sites the corresponding figure was approx. 9%. The CoupModel accurately described general C cycling behaviour in these ecosystems, reproducing the differences between north and south. The simulated changes in SOC pools during the measurement period were small, ranging from -8 g C m(-2) year(-1) in the north to +9 g C m(-2) year(-1) in the south. In contrast, NEE and tree growth measurements at the northernmost site suggest that the soil lost about 90 g C m(-2) year(-1).
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| 2. |
- Andréasson, Frida, et al.
(författare)
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Bioavailability of DOC in leachates, soil matrix solutions and soil water extracts from beech forest floors
- 2009
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Ingår i: Soil Biology & Biochemistry. - : Elsevier BV. - 0038-0717. ; 41:8, s. 1652-1658
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Tidskriftsartikel (refereegranskat)abstract
- The biodegradability of dissolved organic carbon (DOC) in different fractions from the forest floor was studied. Soil leachate (SI, the soil solution in macropores which is freely drained from forest floor after rainfall), the soil matrix solution (SMS, the soil solution in meso-/micropores of the soil matrix), and soil water extracts (SWE) from two different beech forest floors were compared. Zero-tension and tension lysimeters were used to collect SL and SMS, respectively. Loss of DOC (during 21 days) and respiration of CO2-C (during 7 days) were used as conventional measures of the availability of DOC. Bacterial production, measured using the leucine incorporation technique, and bacterial growth efficiency were also estimated. All methods were used to study differences in biodegradability between plots with and without ground flora (Deschampsia flexuosa or Anemone nemorosa) and different type of forest floor (with an organic (O) horizon or a mull (A) horizon). There were no differences in bioavailability of DOC from soil solutions extracted from plots with and without ground flora. The bioavailability of DOC in the different collected soil solutions varied, however. DOC in SWE was the most available, with a mean of 39% of DOC-loss in 21 days, and 18% of DOC being respired in 7 days. DOC in soil matrix solution was the least available of the soil solutions (7% respired), significantly less than DOC in soil leachate (11% respired). The methods measuring biodegradation of DOC, DOC-loss and CO2-C respiration gave similar results and were comparable to bacterial production and bacterial growth efficiency, with the exception of SWE from the O-horizon at the a flexuosa site, which had low bacterial production and bacterial growth efficiency, indicating a limitation of the bacterial growth. This study is one of the first to use bacterial production and bacterial growth efficiency for measuring bioavailability in terrestrial environments, giving an extra dimension for the process of biodegradation of DOC. (C) 2009 Elsevier Ltd. All rights reserved.
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| 3. |
- Andréasson, Frida, et al.
(författare)
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Differences in soil organic matter, extractable nutrients, and acidity in European beech (Fagus sylvatica L.) forest soils related to the presence of ground flora
- 2012
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Ingår i: Journal of Forest Research. - : Informa UK Limited. - 1341-6979 .- 1610-7403. ; 17:4, s. 333-342
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Tidskriftsartikel (refereegranskat)abstract
- Differences in soil organic matter (SOM) content, soil acidity, and soil exchangeable nutrients (NH4-N, NO3-N, Ca, K, Na, Mg) related to the presence of ground flora were studied. The study was carried out for a growing season in two different Fagus sylvatica L. forests in southern Sweden, and the differences in soil characteristics below naturally occurring patches of Deschampsia flexuosa (L.) Trin. or Anemone nemorosa L. were compared with those with no ground flora. Patches of D. flexuosa led to higher soil pH, but lower SOM, water content, base saturation, and NH4-N concentration compared with adjacent zones without D. flexuosa. The lower SOM content suggested an increased rate of decomposition which caused soil pH to increase because of release of basic cations. In the presence of A. nemorosa, pH was higher and the exchangeable acidity lower than for patches without the herb. In early spring, when A. nemorosa emerged and flowered, the NH4-N concentration was somewhat lower in the presence of the herb than when it was absent. For the evergreen grass D. flexuosa NH4-N concentrations were lower in patches with the grass later in the summer season (July). This work indicates the presence of spatial and temporal differences in nutrient circulation and decomposition on the small ground flora scale, which should be considered when studying nutrient and carbon cycles of temperate forests.
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| 4. |
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| 5. |
- Bergkvist, Bo
(författare)
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Changing of Lead and Cadmium Pools of Swedish Forest Soils
- 2001
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Ingår i: Water, Air, & Soil Pollution: Focus. - 1573-2940. ; 1:3-4, s. 371-383
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Tidskriftsartikel (refereegranskat)abstract
- The aims of the paper are to; i)evaluate the rate and direction of present changes in lead (Pb) and cadmium (Cd) soil pools of Swedish forests; ii) discuss processes of importance for leaching of Pb and Cd in Swedish forest soils. The presently ongoing changes of Pb and Cd pools of Swedish forest soils are evaluated by compilation of data from the literature and unpublished sources. It is concluded that Cd pools are presently decreasing in larger areas of Sweden. The rate of decrease is mainly determined by soil acidity status; Cd leaching is regulated by ion exchange with Ca2+, Mg2+, Al3+ and H+, and is higher in acid soils. The Pb pools are presently increasing with 0.1 to 0.3 percent annually in the soil down to 0.5 meter. Pb is redistributed from the O horizon to the B horizon,most pronounced in spruce forests; the Pb pools of the O horizon are presently not increasing, but is slightly decreasing by 0.1 to 0.2 percent annually. The leaching of Pb in the soil is controlled by factors regulating the solubility of organic matter.
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| 6. |
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| 7. |
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| 8. |
- Ekström, Sara, et al.
(författare)
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Effect of Acid Deposition on Quantity and Quality of Dissolved Organic Matter in Soil-Water.
- 2011
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 1520-5851 .- 0013-936X. ; 45:11, s. 4733-4739
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to explore how acid deposition may affect the concentration and quality of dissolved organic matter (DOM) in soil-water. This was done by a small-scale acidification experiment during two years where 0.5 × 0.5 m(2) plots were artificially irrigated with water with different sulfuric acid content, and soil-water was sampled using zero-tension lysimeters under the O-horizon. The DOM was characterized using absorbance, fluorescence, and size exclusion chromatography analyses. Our results showed lower mobility of DOM in the high acid treatment. At the same time, there was a significant change in the DOM quality. Soil-water in the high acid treatment exhibited DOM that was less colored, less hydrophobic, less aromatic, and of lower molecular weight, compared to the low acid treatment. This supports the hypothesis that reduction in sulfur deposition is an important driver behind the ongoing brownification of surface waters in many regions.
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| 9. |
- Fransson, Ann-Mari, et al.
(författare)
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Phosphorus fertilisation causes durable enhancement of phosphorus concentrations in forest soil
- 2000
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Ingår i: Forest Ecology and Management. - 1872-7042. ; 130:1-3, s. 69-76
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Tidskriftsartikel (refereegranskat)abstract
- The duration of P fertiliser in acid forest soil was investigated in a Norway spruce (Picea abies Karst.) forest in southcentral Sweden. The fertilisation of the soil started in 1967, but no P has been applied since 1988. The N fertilisation is still continuing. Totally, 300 kg P per hectare, as superphosphate, and/or 1090 kg N per hectare, as ammonium nitrate, was applied. Concentrations of both 0.05M Na2SO4 + 0.02M NaF extractable P and 0.5M H2SO4 extractable P in the Of, Oh, E and top B horizons of fertilised soils were elevated compared to the control. The P fractions considered to be extracted are adsorbed and some Al-bound phosphate, in the case of Na2SO4 + NaF, and Ca phosphates, in the case of H2SO4. 3-4% of the added P was recovered as Na2SO4 + NaF extractable P, and 10-22% was recovered as H2SO4 extractable P in the soil profile down through the first 5 cm of the B horizon. Still continuing ammonium nitrate fertilisation has decreased the H2SO4 extractable P concentration in this soil. Cumulative P fertiliser application of 300 kg P per hectare has counteracted this decrease. (C) 2000 Elsevier Science B.V. All rights reserved.
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| 10. |
- Fröberg, M, et al.
(författare)
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Concentration and Fluxes of Dissolved Organic Carbon (DOC) in Three Norway Spruce Stands along a Climatic Gradient in Sweden
- 2006
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Ingår i: Biogeochemistry. - : Springer Science and Business Media LLC. - 1573-515X .- 0168-2563. ; 77:1, s. 1-23
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Tidskriftsartikel (refereegranskat)abstract
- Leaching of dissolved organic carbon (DOC) from the forest floor and transport in soil solution into the mineral soil are important for carbon cycling in boreal forest ecosystems. We examined DOC concentrations in bulk deposition, throughfall and in soil solutions collected under the O and B horizons in three Norway spruce stands along a climatic gradient in Sweden. Mean annual temperature for the three sites was 5.5, 3.4 and 1.2 °C. At each site we also examined the effect of soil moisture on DOC dynamics along a moisture gradient (dry, mesic and moist plots). To obtain information about the fate of DOC leached from the O horizon into the mineral soil, 14C measurements were made on bulk organic matter and DOC. The concentration and fluxes of DOC in O horizon leachates were highest at the southern site and lowest at the northern. Average DOC concentrations at the southern, central and northern sites were 49, 39 and 30 mg l−1, respectively. We suggest that DOC leaching rates from O horizons were related to the net primary production of the ecosystem. Soil temperature probably governed the within-year variation in DOC concentration in O horizon leachates, but the peak in DOC was delayed relative to that of temperature, probably due to sorption processes. Neither soil moisture regime (dry, mesic or moist plots) nor seasonal variation in soil moisture seemed to be of any significance for the concentration of DOC leached from the O horizon. The 14C measurements showed that DOC in soil solution collected below the B horizon was derived mainly from the B horizon itself, rather than from the O horizon, indicating a substantial exchange (sorption–desorption reactions) between incoming DOC and soil organic carbon in the mineral soil.
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| 11. |
- Fröberg, M, et al.
(författare)
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Contributions of Oi, Oe and Oa horizons to dissolved organic matter in forest floor leachates
- 2003
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Ingår i: Geoderma. - 0016-7061. ; 113:3-4, s. 311-322
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to identify the role of organic matter of the Oi, Oe and Oa layers for leaching of dissolved organic matter (DOM) from the O horizon in a podsolised forest soil in southern Sweden. Solid state C-13 cross polarization magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy and C-14 measurements were used to analyse organic matter in solid material and water extracts from the Oi, Oe and Oa horizons, soil leachates collected below the Oe and Oa horizons and throughfall. The DOM in soil leachates from the Oe horizon had a C-14 content that was higher than the water extractable organic matter (WEOM) from the Oi horizon but equal to the C-14 content in the WEOM from the Oe horizon. The C-14 contents in WEOM and DOM from the Oe and Oa horizons were all equal. These results suggest that the DOM leaving the Oe horizon to a large extent had its origin within the Oe horizon itself. NMR spectroscopy showed that WEOM was higher in O-alkyl and lower in aromatic carbon than DOM in soil leachates.
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| 12. |
- Fröberg, M, et al.
(författare)
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Dissolved Organic Carbon Leaching from a Coniferous Forest Floor - A Field Manipulation Experiment
- 2005
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Ingår i: Biogeochemistry. - : Springer Science and Business Media LLC. - 1573-515X .- 0168-2563. ; 75:2, s. 271-287
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Tidskriftsartikel (refereegranskat)abstract
- Leaching of dissolved organic carbon (DOC) from the O layer is important for the carbon cycling of forest soils. Here we study the role of the Oi, Oe and Oa horizons in DOC leaching from the forest floor in field manipulations carried out in a Norway spruce forest stand in southern Sweden. The manipulations involved the addition and removal of litter and the removal of Oi, Oe and Oa horizons. Our data suggest that both recent litter and humified organic matter contribute significantly to the leaching of dissolved organic matter from the O layer. An addition of litter corresponding to four times annual litterfall resulted in a 35% increase in DOC concentrations and fluxes although the specific UV absorbance remained unchanged. The removal of litterfall and the Oi horizon resulted in a decreased DOC concentration and in a significant increase in the molar UV absorptivity. The DOC concentration under the Oa horizon was not significantly different from that under the Oe horizon and there were no increase in DOC flux, but rather a decrease, from the bottom of the Oe horizon to the bottom of the Oa horizon, suggesting that there is no net release of DOC in the Oa horizon. However, significant leaching of DOC occurred from the Oa horizon when litterfall and the Oi and Oe horizons were removed. This indicates that there is both a removal of DOC from the Oi and Oe horizons and a substantial production of DOC in the Oa horizon. Quantitatively, we suggest that the Oi, Oe and Oa horizons contributed approximately 20, 30 and 50%, respectively, to the overall leaching of DOC from the O layer.
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| 13. |
- Holmström, Stefan, 1970-, et al.
(författare)
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Evaluation of a Swedish version of the Job Stress Survey
- 2008
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Ingår i: Scandinavian Journal of Psychology. - : Wiley. - 0036-5564 .- 1467-9450. ; 49:3, s. 277-286
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Tidskriftsartikel (refereegranskat)abstract
- The present study assesses and evaluates the psychometric properties of a Swedish version of the Job Stress Survey (JSS; Spielberger, 1991; Spielberger & Vagg, 1999). This instrument is constructed to measure generic sources of occupational stress encountered by employees in a wide variety of work settings, settings that often result in psychological strain. The JSS was administered to metal assembly industry workers and medical service personnel in northern Sweden (n= 1186). The exploratory factor analysis showed that there is a high similarity between the present Swedish version and the original American version. Internal reliabilities of the scales, as well as test-retest reliabilities were shown to be high, and concurrent validity, as examined by comparisons with the Perceived Stress Questionnaire Index ( Levenstein et al., 1993 ) was found to be satisfactory. The consistency of these findings is discussed with particular focus on groups of employees, gender, and cross-cultural evaluations.
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| 14. |
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| 15. |
- Holmström, Stefan, et al.
(författare)
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Job Stress Survey and self-reported health : Evaluating survey stability through repeated measurements in metal-industry workplaces
- 2004
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Ingår i: Proceedings from 36th Annual Conference of the Nordic Ergonomics Society. (NES).
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Level of stress and muskuloskeletal complaints was studied in t wo metal- industry workplaces. Measurements were obtained twice with a 6-month inteIVa!. Level of stress was measured by the Job Stress Survey (Spieiberger & Vagg, 1999). Level of muskuloskeletal complaints was measured by 5-point rating scales. Results showed that the JSS sca!e values, as weil as the muskuloskeletal ratings, were quite stable over the six-month inteIVal. The three JSS scales showed high reliability. The two factories differed with respect to the patteffi of scale values, but these patteros remained over the six months, suggesting that the JSS instrument reflects major stress structures in the factory , rather than occasional changes in production.
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| 16. |
- Holmström, Stefan, et al.
(författare)
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Job Stress Survey and self-reported health : Repeated measurements in metal-industry
- 2004
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Ingår i: Proceedings from 36th Annual Conference of the Nordic Ergonomics Society. (NES).
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Occupational stress and muskuloskeletal complaints was studied in t wo metal-industry workplaces. Measurements were obtained twice with a 6-month interval. Occupational stress was measured by the lob Stress Survey (SpieIberger & Vagg, 1999) and muskuloskeletal complaints was measured by 5-point rating scales. Results showed that the lSS scale values, as weIl as the musculoskeletal pain ratings, were quite stable over the six-month interval. The three lSS scales showed high reliability. The t wo factories differed with respect to the pattern of scale values, but the se patterns remained over the six months, suggesting that the lSS instrument reflects major stress structures in the factory , rather than occasional changes in production.
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| 17. |
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| 18. |
- Holmström, Stefan, 1970-
(författare)
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Workplace stress measured by Job Stress Survey and relationships to musculoskeletal complaints
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main purpose of this thesis was to evaluate and test the Job Stress Survey (JSS, Spielberger, 1991; Spielberger & Vagg, 1999), a self-report instrument which assesses workplace stress. In the thesis a thorough evaluation is made of JSS scales and items, and the relations to health, particularly musculoskeletal complaints. The aim of Study I was to evaluate the factor structure and the psychometric properties of a Swedish version of the JSS. The instrument was distributed to medical service personal and metal industry workers (n=1186). Factor analyses demonstrated a good resemblance between the present version and the American original version. The results also showed that the internal consistencies, as well as the test-retest reliabilities of the scales are high, and the concurrent validity are good. Study II examined work-related stress measured by JSS for the subgroups of gender, industry workers and medical service personnel, and special attention was given to the problem of differential item functioning (DIF) on these subgroups. The main findings were that both gender and occupation has a substantial impact on specific sources of work-related stress assessed by JSS scales and individual items. The result of the DIF analyses showed no item bias in the gender subgroup, but for the occupational subgroups there where items showing DIF in two of the scales. These items do not jeopardize the conclusions made on scale level since the number of items showing DIF are too few to make an impact on the overall result on the different scales. In Study III the relation between self-reported stress and health, particularly musculoskeletal problems were examined longitudinally in two metal industry factories. Results showed high levels of stress and musculoskeletal complaints in these factories and significant and strong relationships between the JSS scales and musculoskeletal, as well as psychosocial ratings. Lack of Organizational Support was found to be more related to musculoskeletal pain than Job Pressure. Longitudinal differences were found between the factories and between different types of musculoskeletal complaints. The general conclusions from the studies are that the present version of JSS shows a good resemblance with the American original, and that JSS is a useful instrument for studying relationships between stress and health.
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| 19. |
- Lindemalm, Christina, et al.
(författare)
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Immune response, depression and fatigue in relation to support intervention in mammary cancer patients
- 2008
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Ingår i: Supportive Care in Cancer. - : Springer Science and Business Media LLC. - 0941-4355 .- 1433-7339. ; 16:1, s. 57-65
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Tidskriftsartikel (refereegranskat)abstract
- Goal of work To study the effect of support intervention on immune function in breast cancer patients. Materials and methods Breast cancer patients from an ongoing prospective randomised quality-of -life study were chosen for assaying immune functions in relation to a support-group intervention program running on a residential basis. Twenty-one women received adjuvant-combined radio-chemotherapy (CT-RT) and 20 women radiotherapy (RT). Eleven CT-RT and ten RT patients were randomised to support-group intervention, the rest served as controls. Immune tests for NK cells and NK-cell cytotoxicity, as well as lymphocyte subpopulations and response to antigen were performed before intervention, 2, 6, and 12 months later, in parallel to controls and healthy volunteers (n=11). Depression, anxiety and fatigue were evaluated by the Hospital Anxiety and Depression (HAD) and the Norwegian Fatigue questionnaire. The density of NK cell receptors and in vitro quantitation of functional NK cytotoxicity against K562 cell line were evaluated. Four-colour flow cytometry was used to detect signal transduction molecules and cytokine expression. T-cell proliferate response to purified protein derivate (PPD) antigen was evaluated. Results No significant immune effect of support intervention could be found. The immune variables were severely disarranged compared to healthy volunteers but showed a statistically significant improvement over time. The majority of patients suffered from fatigue but had low scores for depression and anxiety. Conclusion No effect on immune parameters could be detected from support intervention. The long-lasting immune suppression might override a putative effect of the intervention. Low depression scores may contribute to the absence of a detectable effect.
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| 20. |
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| 21. |
- Mozaffari, Fariba, et al.
(författare)
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Systemic immune effects of adjuvant chemotherapy with 5-fluorouracil, epirubicin and cyclophosphamide and/or radiotherapy in breast cancer : a longitudinal study
- 2009
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Ingår i: Cancer Immunology and Immunotherapy. - : Springer Science and Business Media LLC. - 0340-7004 .- 1432-0851. ; 58:1, s. 111-120
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Tidskriftsartikel (refereegranskat)abstract
- Immunotherapy is being increasingly utilized for adjuvant treatment for breast cancer (BC). We have previously described immune functions during primary therapy for BC. The present study describes immune recovery patterns during long-term, unmaintained follow-up after completion of adjuvant therapy. A group of patients with primary BC had been treated with adjuvant radio-chemotherapy therapy (RT + CT) 5-fluorouracil, epirubicin and cyclo-phosphamide (FEC) (n = 21) and another group with radiotherapy (RT) (n = 20) alone. Immunological testing of NK and T-cell functions was performed initially at the end of adjuvant treatment and repeated after 2, 6 and 12 months. NK cell cytotoxicity was significantly higher (P < 0.05) at all time-points in patients than in age-matched controls and did not differ between the two treatments groups during one year observation. In contrast, lower numbers of CD4 T-cells and lower expression of CD28 on T-cells was observed particularly in RT + CT patients and did not normalize during the observation period. The numbers of T-reg cells (CD4(+) CD25(high)) were low in the RT + CT group during follow-up, as well as expression of TCR xi, Zap70, p56(lck), P59(fyn) and PI3 k in CD4+ cells. In contrast, expression of intracellular cytokines (IFN-gamma, IL-2, IL-4) in CD4 and CD8 T cells were signiWcantly higher in RT + CT patients than in the RT group and the difference increased during follow-up. In conclusion, NK-cell cytotoxicity increased during unmaintained long-term follow-up whereas CD4 and regulatory T cells as well as signal transduction molecules remained low following adjuvant radio-chemotherapy.
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| 22. |
- Sjöberg, G, et al.
(författare)
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Long-term N addition effects on the C mineralization and DOC production in mor humus under spruce
- 2003
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Ingår i: Soil Biology & Biochemistry. - 0038-0717. ; 35:10, s. 1305-1315
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Tidskriftsartikel (refereegranskat)abstract
- This study was based on laboratory incubations of mor humus from two N fertilized stands of Norway spruce in Sweden (Skogaby and Strasan), which had received repeated N additions (100 kg N ha(-1) yr(-1) as (NH4)(2)SO4 at Skogaby and 35, 73 and 108 kg ha(-1) yr(-1), as NH4NO3 at Strasan) during 8 and 24-29 years, respectively. The aim was to investigate long-term N effects on the mineralization of C and production of DOC. Mor humus (Oe and Oa) was incubated in columns at 20 degreesC for 49 days. Columns were leached once a week with artificial throughfall solution, which was analyzed for DOC, total N, NH4+-N and NO3--N. Prior to each leaching event, CO2 evolution from the columns was determined. C-to-N ratios in the N-treated Oe layers at Strasan (21-24) and Skogaby (24) were significantly lower than those of the controls (Strasan, 32; Skogaby, 28). The cumulative amount Of CO2-C showed a significant treatment effect in the Oe layer at Skogaby, i.e. 18 and 29 mg C g(-1) C in the N treatment and control, respectively. At Strasan, the cumulative CO2-C was significantly lower in the N3 treatment compared to the control in both layers (33 compared to 74 mg C g(-1) C in the Oe layer and 16 compared to 35 mg C g(-1) C in the Oa layer). Neither the DOC nor the DON production showed any significant treatment effects at the two sites. However, DOC was lower in the fertilized Oe layer at Skogaby throughout the incubation. The leaching of DON was highest in the Oe layers at both sites, and DON increased with time at Skogaby while there was a decreasing trend at Strasan. The DOC-to-DON ratio tended to be lower in the fertilized Oe layers at both sites. The NH4+ leaching at Skogaby decreased in the N-treated Oe and Oa layers. At Strasan, NH4+ from the Oe layer increased in N2 and control. The NO3- leaching was low and constant in both Skogaby layers. At Strasan, NO3- increased in the Oe layer of N1. Cumulative CO2 was positively correlated to C-to-N ratio (r(2) = 0.71, p < 0.01) and to cumulative DOC (r(2) = 0.63, p < 0.05) in the Oe layer at Strasan. Our conclusion was that long-term N additions caused decreased C-to-N ratios and decreased CO2 evolution rates. The correlation between CO2 and C-to-N ratio in the Oe layers at Strasan may be due to a changed quality of the fertilized forest floor material and presence of more N efficient microorganisms.
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| 23. |
- Söderfjell, Stefan, 1970-, et al.
(författare)
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Musculoskeletal pain complaints and performance on cognitive tasks over the adult life span
- 2006
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Ingår i: Scandinavian Journal of Psychology. - : Wiley. - 0036-5564 .- 1467-9450. ; 47:5, s. 349-359
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Tidskriftsartikel (refereegranskat)abstract
- The present study aimed at comparing participants with and without self reported musculoskeletal pain in a normal population with regard to performance on a range of tests for episodic memory, semantic memory, and other cognitive functions and to see if expected differences interacted with age. The results showed that participants with pain performed worse on a range of tasks as compared to participants without pain, and that these differences occurred regardless of age. The most robust effects of pain were displayed on tests for vocabulary and construction ability as these were the only effects that remained significant after controlling for years of education and reported depression in separate analyses. When depression and education were controlled for in the same analysis, even these effects were eliminated, suggesting interplay between pain, depressive status, and educational level in the negative effects on cognitive functioning.
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| 24. |
- Tipping, E, et al.
(författare)
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DOC leaching from a coniferous forest floor: modeling a manipulation experiment
- 2005
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Ingår i: Journal of Plant Nutrition and Soil Science. - : Wiley. - 1436-8730 .- 1522-2624. ; 168:3, s. 316-324
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Tidskriftsartikel (refereegranskat)abstract
- The DyDOC model simulates the C dynamics of forest soils, including the production and transport of dissolved organic matter (DOM), on the basis of soil hydrology, metabolic processes, and sorption reactions. The model recognizes three main pools of soil C: litter, substrate (an intermediate transformation product), and humic substances. The model was used to simulate the behavior of C in the 0 horizon of soil under a Norway spruce stand at Asa, Sweden, that had been subjected to experimental manipulations (addition and removal) of above-ground litter inputs and to removal of the Oi and Oe layers. Initially, the model was calibrated using results for the control plots and was able to reproduce the observed total soil C pool and C-14 content, DOC flux and DO C-14 content, and the pool of litter C, together with the assumed content of C in humic substances (20% of the total soil C), and the assumed distribution of DOC between hydrophilic and hydrophobic fractions. The constant describing DOC exchange between micro- and macropores was estimated from short-term variations in DOC concentration. When the calibrated model was used to predict the effects of litter and soil manipulations, it underestimated the additional DOC export (up to 33%) caused by litter addition, and underestimated the 22% reduction in DOC export caused by litter withdrawal. Therefore, an additional metabolic process, the direct conversion of litter to DOC, was added to the model. The addition of this process permitted reasonably accurate simulation of the results of the manipulation experiments, without affecting the goodness-of-fit in the model calibration. The results suggest that, under normal conditions, DOC exported from the Asa forest floor is a mixture of compounds derived from soil C pools with a range of residence times. Approximately equal amounts come from the litter pool (turnover time 4.6 yr), the substrate pool (26 yr), and the humic-substances pool (36 yr).
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| 25. |
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| 26. |
- Wiman, Bo, et al.
(författare)
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Perspectives on Aerosol Deposition to Natural Surfaces: interactions between aerosol residence times, removal processes, the biosphere and global environmental change
- 1990
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Ingår i: Journal of Aerosol Science. - 0021-8502 .- 1879-1964. ; 21:3, s. 313-338
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Tidskriftsartikel (refereegranskat)abstract
- This paper summarizes the state-of-the-art and the research needs in the areas of aerosol residence-time assessments, deposition modelling, and understanding of aerosols in biogeochemistry. Research needs are emphasized from a systems perspective of global environmental change. Although fundamental quantitative knowledge is lacking, some qualitative linkages between source strengths, residence times, removal processes and the biosphere can be identified. It turns out that not only are the respective areas as such challenged by new problems, superimposed on the fairly well established conventional ones, but these areas also face mutually operating sets of feedbacks between residence times and sink/source characteristics of ecological systems subject to stress. To evaluate the sensitivity of these feedback loops, and to assess whether they are negative (stabilizing interactions) or positive (destabilizing) are important and potentially urgent tasks. Such studies should focus on a common goal, such as developing empirical and theoretical understanding of aerosol resuspension, transport and deposition for application in large-scale circulation models. A basic link in such advancements is that structural change of vegetated surfaces of the biosphere caused by deposition itself, and by changing land-use and climate, be understood and assessed. This article was initiated in connection with the Workshop on Aerosol Deposition to Natural Surfaces, Lund, Sweden, 2 September, 1988; conducted during the European Aerosol Conference (see J. Aerosol Sci. 19, 775–776). The authors wish to express their thanks to the workshop participants (list available from the workshop coordinators).
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| 27. |
- Åkerblom, Staffan, et al.
(författare)
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Partitioning of Hg between solid and dissolved organic matter in the humus layer of boreal forests
- 2008
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Ingår i: Water, Air and Soil Pollution. - : Springer Science and Business Media LLC. - 1573-2932 .- 0049-6979. ; 189:1-4, s. 239-252
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Tidskriftsartikel (refereegranskat)abstract
- The mobility of mercury (Hg) deposited on soils controls the concentration and toxicity of Hg within soils and in nearby streams and lakes, but has rarely been quantified under field conditions. We studied the in situ partitioning of Hg in the organic top layer (mor) of podsols at two boreal forest sites differing in Hg deposition and climatic regime (S. and N. Sweden, with pollution declining to the north). Soil solution leaching from the mor layer was repeatedly sampled using zero-tension lysimeters over 2 years, partly in parallel with tension lysimeters. Concentrations of Hg and dissolved organic carbon (DOC) were higher while pH was lower at the southern site (means +/- SD: Hg=44 +/- 15 ng L-1, DOC=63.0 +/- 31.3 mg L-1, pH=4.05 +/- 0.53) than at the northern site (Hg=22 +/- 6 ng L-1, DOC=41.8 +/- 12.1 mg L-1, pH=4.28 +/- 0.43). There was a positive correlation over time between dissolved Hg and DOC at both sites, even though the DOC concentration peaked during autumn at both sites, while the Hg concentration remained more constant. This correlation is consistent with the expected strong association of Hg with organic matter and supports the use of Hg/C ratios in assessments of Hg mobility. In the solid phase of the overlying O-f layer, both Hg concentrations and Hg/C ratios were higher at the southern site (means +/- SD: 0.34 +/- 0.06 mu g g(-1) dw and 0.76 +/- 0.14 mu g g(-1) C, respectively) than at the northern site (0.31 +/- 0.05 mu g g(-1) dw and 0.70 +/- 0.12 mu g g(-1) C, respectively). However, concentrations in the solid phase differed less than might be expected from the difference in current atmospheric input, suggesting that the fraction of natural Hg is still substantial. At both sites, Hg/C ratios in the upper half of the mor layer were only about two thirds of those in the lower half, suggesting that the recent decrease in anthropogenic Hg deposition onto the soil is offset by a natural downward enrichment of Hg due to soil decomposition or other processes. Most interestingly, comparison with soil leachate showed that the average Hg/C ratios in the dissolved phase of the mor layers at both sites did not differ from the average Hg/C ratios in the overlying solid organic matter. These results indicate a simple mobilisation with negligible fractionation, despite differences in Hg deposition patterns, soil chemistry and climatic regimes. Such a straight-forward linkage between Hg and organic matter greatly facilitates the parameterisation of watershed models for assessing the biogeochemical fate, toxic effect and critical level of atmospheric Hg input to forest soils.
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