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- GUSTAFSSON, L, et al.
(författare)
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LOW GENETIC-VARIATION IN SWEDISH POPULATIONS OF THE RARE SPECIES VICIA-PISIFORMIS (FABACEAE) REVEALED WITH RFLP (RDNA) AND RAPD
- 1994
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Ingår i: Plant Systematics and Evolution. - 0378-2697 .- 1615-6110. ; 189:3-4, s. 133-148
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Tidskriftsartikel (refereegranskat)abstract
- Nine Swedish populations, 1-5 individuals/population, and one cultivated individual of the rare species Vicia pisiformis were investigated for genetic variation. In hybridizations with two rDNA probes using 8 restriction enzymes, only two individuals belonging to one population were polymorphic. A map of the rDNA gene cluster was constructed for four of the restriction enzymes used. Two of the polymorphic sites were mapped and were found to be located outside regions coding for rRNA, presumably caused by single point mutations or small deletions. The repeat length of the rDNA region was c. 10,000 bp, which corresponds well with the size found for other species belonging to Fabaceae. No length polymorphism was found in the intergenic spacer, contrary to the situation found for most other plant species investigated for rDNA variation. The haplotype diversity for the species (Hsp Shannon) was very low (0.055). Within-population values (Hpop) was 0 for all populations except the variable one, which had 0.301. PCR amplification with 6 random primers also revealed very low levels of genetic diversity. A polymorphism was observed in a limited number of individuals for four populations. Hsp was 0.065 and HpopBAR was 0.050. The average D value (Wetton) for the PCR haplotypes was 0.99.
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| 2. |
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| 3. |
- Adediran, Gbotemi A., et al.
(författare)
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Phosphorus in 2D : Spatially resolved P speciation in two Swedish forest soils as influenced by apatite weathering and podzolization
- 2020
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Ingår i: Geoderma. - : Elsevier BV. - 0016-7061 .- 1872-6259. ; 376
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Tidskriftsartikel (refereegranskat)abstract
- The cycling and long-term supply of phosphorus (P) in soils are of global environmental and agricultural concern. To advance the knowledge, a detailed understanding of both the vertical and lateral variation of P chemical speciation and retention mechanism(s) is required, a knowledge that is limited in postglacial forest soils. We combined the use of synchrotron X-ray fluorescence microscopy with multi-elemental co-localisation analysis and P K-edge XANES spectroscopy to reveal critical chemical and structural soil properties. We established a two-dimensional (2D) imagery of P retention and speciation at a microscale spatial resolution in two forest soil profiles formed in glaciofluvial and wave-washed sand. The abundance and speciation of P in the upper 40 cm was found to be influenced by soil weathering and podzolization, leading to spatial variability in P speciation on the microscale (< 200 pm) with P existing predominantly as organic P and as PO4 adsorbed to allophane and ferrihydrite, according to XANES spectroscopy. These species were mostly retained at sharp edges and in pore spaces within Al and Si-bearing particles. Despite the relatively young age ( < 15,000 years) of the soils, our results show primary mineral apatite to have weathered from the surface horizons. In the C horizon however, a large fraction of the P was in the form of apatite, which appeared as widely dispersed ( > 600 pm) hot spots of inclusions in aluminosilicates or as discrete micro-sized apatite grains. The subsoil apatite represents a pool of P that trees can potentially acquire and thus add to the biogeochemically active P pool in temperate forest soils.
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| 4. |
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| 5. |
- Adediran, Gbotemi, et al.
(författare)
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Micro and nano sized particles in leachates from agricultural soils: Phosphorus and sulfur speciation by X-ray micro-spectroscopy
- 2021
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 189
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Tidskriftsartikel (refereegranskat)abstract
- Colloids and nanoparticles leached from agricultural land are major carriers of potentially bioavailable nutrients with high mobility in the environment. Despite significant research efforts, accurate knowledge of macronutrients in colloids and nanoparticles is limited. We used multi-elemental synchrotron X-ray fluorescence (XRF) microscopy with multivariate spatial analysis and X-ray atomic absorption near-edge structure (XANES) spectroscopy at the P and S K-edges, to study the speciation of P and S in two fractions of leached particles, >0.45 and <0.45 mu m respectively, collected from four tile-drained agricultural sites in Sweden. P K-edge XANES showed that organic P, followed by P adsorbed to surfaces of aluminum-bearing particles were the most common forms of leached P. Iron-bound P (Fe-P) forms were generally less abundant (0-30 % of the total P). S K-edge XANES showed that S was predominantly organic, and a relatively high abundance of reduced S species suggests that redox conditions were adverse to the persistence of P bound to Fe-bearing colloids in the leachates. Acid ammonium-oxalate extractions suggested that P associated with Al and Fe (Al-P and Fe-P) in most cases could be explained by the adsorption capacity of non-crystalline (oxalate-extractable) oxides of Al and Fe. These results improve our understanding of particulate P and S speciation in the vadose zone and helps in developing effective technologies for mitigating colloidal driven eutrophication of water bodies near agricultural land. (C) 2020 The Author(s). Published by Elsevier Ltd.
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| 6. |
- Akselsson, Cecilia, et al.
(författare)
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Weathering rates in Swedish forest soils
- 2019
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 16:22, s. 4429-4450
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Forskningsöversikt (refereegranskat)abstract
- Soil and water acidification was internationally recognised as a severe environmental problem in the late 1960s. The interest in establishing “critical loads” led to a peak in weathering research in the 1980s and 1990s, since base cation weathering is the long-term counterbalance to acidification pressure. Assessments of weathering rates and associated uncertainties have recently become an area of renewed research interest, this time due to demand for forest residues to provide renewable bioenergy. Increased demand for forest fuels increases the risk of depleting the soils of base cations produced in situ by weathering. This is the background to the research programme Quantifying Weathering Rates for Sustainable Forestry (QWARTS), which ran from 2012 to 2019. The programme involved research groups working at different scales, from laboratory experiments to modelling. The aims of this study were to (1) investigate the variation in published weathering rates of base cations from different approaches in Sweden, with consideration of the key uncertainties for each method; (2) assess the robustness of the results in relation to sustainable forestry; and (3) discuss the results in relation to new insights from the QWARTS programme and propose ways to further reduce uncertainties. In the study we found that the variation in estimated weathering rates at single-site level was large, but still most sites could be placed reliably in broader classes of weathering rates. At the regional level, the results from the different approaches were in general agreement. Comparisons with base cation losses after stem-only and whole-tree harvesting showed sites where whole-tree harvesting was clearly not sustainable and other sites where variation in weathering rates from different approaches obscured the overall balance. Clear imbalances appeared mainly after whole-tree harvesting in spruce forests in southern and central Sweden. Based on the research findings in the QWARTS programme, it was concluded that the PROFILE/ForSAFE family of models provides the most important fundamental understanding of the contribution of weathering to long-term availability of base cations to support forest growth. However, these approaches should be continually assessed against other approaches. Uncertainties in the model approaches can be further reduced, mainly by finding ways to reduce uncertainties in input data on soil texture and associated hydrological parameters but also by developing the models, e.g. to better represent biological feedbacks under the influence of climate change.
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| 7. |
- Andersson, Anders, et al.
(författare)
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A transcriptional timetable of autumn senescence
- 2004
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Ingår i: Genome Biology. - : Springer Science and Business Media LLC. - 1465-6906 .- 1474-760X. ; 5:4, s. R24-
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Tidskriftsartikel (refereegranskat)abstract
- Background We have developed genomic tools to allow the genus Populus (aspens and cottonwoods) to be exploited as a full-featured model for investigating fundamental aspects of tree biology. We have undertaken large-scale expressed sequence tag (EST) sequencing programs and created Populus microarrays with significant gene coverage. One of the important aspects of plant biology that cannot be studied in annual plants is the gene activity involved in the induction of autumn leaf senescence. Results On the basis of 36,354 Populus ESTs, obtained from seven cDNA libraries, we have created a DNA microarray consisting of 13,490 clones, spotted in duplicate. Of these clones, 12,376 (92%) were confirmed by resequencing and all sequences were annotated and functionally classified. Here we have used the microarray to study transcript abundance in leaves of a free-growing aspen tree (Populus tremula) in northern Sweden during natural autumn senescence. Of the 13,490 spotted clones, 3,792 represented genes with significant expression in all leaf samples from the seven studied dates. Conclusions We observed a major shift in gene expression, coinciding with massive chlorophyll degradation, that reflected a shift from photosynthetic competence to energy generation by mitochondrial respiration, oxidation of fatty acids and nutrient mobilization. Autumn senescence had much in common with senescence in annual plants; for example many proteases were induced. We also found evidence for increased transcriptional activity before the appearance of visible signs of senescence, presumably preparing the leaf for degradation of its components.
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| 10. |
- Apul, Defne S., et al.
(författare)
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Geochemical Modeling of Trace Element Release from Biosolids
- 2010
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Ingår i: Environmental Engineering Science. - : Mary Ann Liebert. - 1092-8758 .- 1557-9018. ; 27:9, s. 743-755
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Tidskriftsartikel (refereegranskat)abstract
- Biosolids-borne trace elements may be released to the environment when biosolids are used as fertilizers in farm land. Trace element leachate concentrations from biosolids are known to be limited by both organic and inorganic sorbent surfaces; this experimental evidence has not been previously verified with geochemical modeling of sorption reactions. In this study, pH-dependent leaching experiments and sorption isotherm experiments were coupled with a multisurface geochemical modeling approach. Biosolids samples were obtained from Toledo and Chicago wastewater treatment plants; their sorbent surfaces were defined and modeled as a combination of organic matter (OM) and Fe-, Al-, and Mn-oxides. The multisurface geochemical modeling approach was partially successful in predicting the pH-dependent leachate concentrations of As, Cd, Cr, Cu, Mo, Ni, and Zn. Both modeled and experimental data indicated that As and Mo in biosolids were bound to Fe- oxides; Cd, Cr, and Cu were bound mainly to OM; and as pH increased the fractions of Cd and Cu bound to Fe- oxides in the biosolids matrix increased. Ni and Zn were distributed between OM and Fe- oxides, and the percentage of each fraction depended on the pH. This study showed that the multisurface geochemical model could be used to generate As (and to a lesser extent Cd) Freundlich isotherm parameters for biosolids. However, the composition and reactivity of solid and dissolved OM was identified as a source of uncertainty in the modeling results. Therefore, more detailed studies focusing on the reactivity of isolated biosolids OM fractions with regard to proton and metal binding are needed to improve the capability of geochemical models to predict the fate of biosolids-borne trace metals in the environment.
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