| 1. |
- Abubaker, Jamal, et al.
(författare)
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Bacterial community structure and microbial activity in different soils amended with biogas residues and cattle slurry
- 2013
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393 .- 1873-0272. ; 72, s. 171-180
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Tidskriftsartikel (refereegranskat)abstract
- Anaerobic digestion of organic materials generates residues of differing chemical composition compared to undigested animal manures, which may affect the soil microbial ecosystem differently when used as fertilizers. This study investigated the effects of two biogas residues (BR-A and BR-B) and cattle slurry (CS) applied at rates corresponding to 70 kg NH4+-N ha(-1) on bacterial community structure and microbial activity in three soils of different texture (a sandy, a clay and an organic clay soil). 16S rRNA genes were targeted in PCR reactions and bacterial community profiles visualized using terminal restriction fragment length polymorphism. General microbial activity was measured as basal respiration (B-resp), substrate-induced respiration (SIR), specific growth rate (mu(SIR)), metabolic quotient (qCO(2)) and nitrogen mineralization capacity (NMC). Non-metric multidimensional scaling analysis visualized shifts in bacterial community structure related to microbial functions. There were significant differences in bacterial community structure after 120 days of incubation (+20 degrees C at 70% of WHC) between non-amended (control) and amended soils, especially in the sandy soil, where CS caused a more pronounced shift than biogas residues. Terminal-restriction fragment (TRF) 307, the predominant peak in CS-amended sandy soil, was identified as possibly Bacillus or Streptococcus. TRF 226, the dominant peak in organic soil amended with BR-B, was classified as Rhodopseudomonas. B-resp significantly increased and SIR decreased in all amendments to organic soil compared with the control, potentially indicating decreased efficiency of heterotrophic microorganisms to convert organic carbon into microbial biomass. This was also reflected in an elevated qCO(2) in the organic soil. The mu(SIR) level was higher in the sandy soil amended with BR-A than with BR-B or CS, indicating a shift toward species capable of rapidly utilizing glucose. NMC was significantly elevated in the clay and organic soils amended with BR-A and BR-B and in the sandy soil amended with BR-B and CS. Thus, biogas residues and cattle slurry had different effects on the bacterial community structure and microbial activity in the three soils. However, the effects of biogas residues on microbial activities were comparable in magnitude to those of cattle slurry and the bacterial community structure was less affected. Therefore, we do not see any reason not to recommend using biogas residues as fertilizers based on the results presented. (C) 2013 Elsevier B.V. All rights reserved.
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| 2. |
- Abubaker, Jamal, et al.
(författare)
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Short-Term Effects of Biogas Digestates and Pig Slurry Application on Soil Microbial Activity
- 2015
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Ingår i: Applied and Environmental Soil Science. - : Hindawi Limited. - 1687-7667 .- 1687-7675. ; 2015, s. 1-15
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Tidskriftsartikel (refereegranskat)abstract
- The effect of four biogas digestates (BD-A, BD-B, BD-C, and BD-D) and pig slurry (PS) on soil microbial functions was assessed at application rates corresponding to 0–1120 kg-N ha−1. At dose corresponding to 140 kg-N ha−1, 30.9–32.5% of the carbon applied in BD-A, BD-C, and PS was utilized during 12 days, while for BD-B and BD-D corresponding utilization was 19.0 and 16.9%, respectively. All BDs resulted in net nitrogen assimilation at low rates (17.5–140 kg-N ha−1) but net mineralization dominated at higher rates. PS resulted in net mineralization at all application rates. All residues inhibited potential ammonium oxidation (PAO), with EC50-values ranging between 45 and 302 kg-N ha−1. Low rates of BDs appeared to weakly stimulate potential denitrification activity (PDA), while higher rates resulted in logarithmic decrease. The EC50-values for PDA were between 238 and 347 kg-N ha−1. No inhibition of PDA was observed after amendment with PS. In conclusion, biogas digestates inhibited ammonia oxidation and denitrification, which could be an early warning of potential hazardous substances in the digestates. However, this effect can also be regarded as positive, since it may reduce nitrogen losses.
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| 3. |
- Azzi, Elias, et al.
(författare)
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Guidelines for estimation of biochar durability : Background report
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Biochar is produced by heating biomass in the total or partial absence of oxygen. This report addresses the long-term persistence of biochar in soil and how this can be managed in climate calculations and reporting. The report consists of this summary and four chapters, which can be read independently.Different terms have been used to describe the durability of biochar carbon storage, but also the physical presence of biochar in soils, e.g. persistence, permanence, recalcitrance, residence times, stability. Today, the term “durability of carbon storage” is preferred in policy contexts, but various academic disciplines such as soil science have other established terms like “persistence”. Here, both durability and persistence are used, rather interchangeably. It is important to be aware of differences in meaning that exist between disciplines.The purpose of this report is to present the state of knowledge regarding the proportion of carbon in biochar that remains in the soil over time and provide recommendations for calculating this. There is a need to calculate the persistence of biochar in soil for national climate reporting, corporate climate reporting, carbon credit trading, and life cycle assessments for various purposes.On the persistence of biocharThe amount of biochar remaining after a certain time depends on the properties of the biochar and the environment in which it is located. Nearly all research on biochar persistence has focused on its application in agricultural soils.The main reason for the high durability of biochar carbon storage is the formation of fused aromatic stable structures during biomass pyrolysis. A high degree of fused aromatic structures makes biochar much less prone to microbial decomposition than fresh biomass.Different biochars have different properties, and this influences how long they persist in the soil. To achieve biochar with properties that provide higher persistence, it should be produced at higher temperatures for a sufficient duration.Measuring and calculating biochar persistenceEstablished quantification methods of 100-year biochar persistence (e.g. referenced in IPCC inventory guidelines and used in voluntary carbon markets, to date) extrapolate short-term soil decomposition processes, and do not fully consider the processes that may explain millennial persistence.Calculations regarding biochar persistence have traditionally used a time span of 100 years to describe the amount of remaining carbon after a certain time. The use of specifically 100 years lacks a well founded scientific reason, but has been regarded as “far enough” into the future from a climate perspective and close enough for modelling to be meaningful.An active area of research relevant for the understanding biochar carbon storage durability is the development of advanced analytical characterisation methods of biochar that will enable measurement of the physicochemical heterogeneity in carbon structures present in biochar.Another area of continued research is biochar incubation, with a focus on field conditions, to elucidate both differences from laboratory conditions, and how transport processes affect biochar in the field.Recommendation and conclusionIn the project, available research data has been aggregated into a functional model that calculates how much of the carbon in biochar remains after a given number of years. The model is based on the H/C ratio of the biochar placed in the soil and the annual average temperature at the location.The model is made freely accessible to provide biochar market actors with the best available knowledge for estimating the durability of biochar carbon.Existing research results provide a sufficient foundation for estimation of the amount of biochar expected to remain over time. Future research results are expected to lead to increased knowledge regarding the decomposition properties of biochar, in particular biochars with a very low H/C ratio. Therefore, this recommendation will be revised by the end of the project in 2025.
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| 4. |
- Azzi, Elias, et al.
(författare)
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Modelling biochar long-term carbon storage in soil with harmonized analysis of decomposition data
- 2024
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Ingår i: Geoderma. - 0016-7061 .- 1872-6259. ; 441
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Tidskriftsartikel (refereegranskat)abstract
- The climate change mitigation benefits of biochar systems arise largely from carbon storage in biochar. However, while biochar is increasingly recognized as a carbon dioxide removal technology, there are on-going scientific discussions on how to estimate the persistence of biochar carbon when biochar is used in soils. Estimates vary from decades to millennia, building on different modelling approaches and evidence. Here, we revisited the persistence estimates derived from extrapolation of biochar incubation experiments, with the aims of making incubation data available, modelling choices transparent, and results reproducible. An extensive dataset of biochar incubations, including 129 biochar decomposition time series, was compiled and is made available alongside code for its analysis. Biochar persistence correlations were sensitive to data selection procedures and to the curve fitting modelling step, while soil temperature adjustments methods had less impact. Biochar H/C ratio remained the main predictor of biochar persistence, in line with previous research, regardless of the extrapolation assumptions (multi-pool exponential functions or power function) used in curve fitting. The relation between H/C and percentage of biochar carbon remaining after 100 years (BC100) was better explained by a power model than a linear model, with R2 values between 0.5 and 0.9. Using multi-pool exponential functions, estimated BC100 varied between 90 % and 60 % for H/C from 0 to 0.7. However, using power functions, BC100 was constrained between 90 % and 80 % for the same H/C range. Additional information about the biochar, the pyrolysis conditions or the environmental incubation conditions did not significantly increase explained variance. Notably, the dataset lacks observations at H/C ratios below 0.2, of biochar made from manure and biosolids, biochar from processes other than slow pyrolysis, field studies, and incubation temperatures below 10 °C, which should guide future experimental work. The detailed analysis performed in this study does not cast doubts on the longevity of biochar carbon storage; rather, it confirms previous knowledge by critically examining the modelling, elucidating the assumptions and limitations, and making the analysis fully reproducible. There is a need for further interdisciplinary work on integration of various theories and approaches to biochar persistence, ultimately leading to the formulation of policy-relevant conclusions.
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| 5. |
- Cederlund, Harald, et al.
(författare)
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Adsorption of Pesticides with Different Chemical Properties to a Wood Biochar Treated with Heat and Iron
- 2016
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Ingår i: Water, Air, and Soil Pollution. - : Springer Science and Business Media LLC. - 0049-6979 .- 1573-2932. ; 227
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Tidskriftsartikel (refereegranskat)abstract
- Biochars are known to affect the environmental fate of pesticides when used as soil amendments and have been suggested to be useful as cheap adsorbents of organic contaminants. We studied the ability of a wood based biochar produced by slow pyrolysis from a mixture of about 80 % hardwood (Belida sp.) and 20 % softwood (Picea abies) to adsorb pesticides in order to assess its potential use as a filter material to prevent point source pollution in agriculture. The pesticides bentazone, chlorpyrifos, diuron, glyphosate and (4-chloro-2-methylphenoxy)acetic acid (MCPA) were used as model compounds. Their adsorption and desorption to the biochar were tested before and after it had been subjected to treatments with heat and/or iron intended to enhance its adsorptive properties. The adsorption affinity of the native biochar, as indicated by the Freundlich K-F value, varied greatly and decreased in the order diuron > chlorpyrifos > MCPA > bentazone > glyphosate. Activation with heat (t=450 degrees C) increased the specific surface area and the wettability of the biochar, measured by a water drop penetration time assay, and increased the adsorption of bentazone and MCPA. Treatment with iron salts, which partially coated the biochar with an iron oxide identified as magnetite, decreased the specific surface area but increased the adsorption of glyphosate. Mixing biochar fractions subjected to different treatments was a successful approach for optimising the adsorption of all model compounds and could be a viable path for creating a versatile yet comparably cheap filter material.
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| 6. |
- Cederlund, Harald, et al.
(författare)
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Degradation and Leaching of Fluroxypyr after Application to Railway Tracks
- 2012
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Ingår i: Journal of Environmental Quality. - : Wiley. - 0047-2425 .- 1537-2537. ; 41, s. 1884-1892
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Tidskriftsartikel (refereegranskat)abstract
- Fluroxypyr is an auxin-type herbicide used for postemergent control of broad-leaved weeds in agriculture and in nonagricultural environments such as railways. The overall aim of this study was to assess the potential environmental impact from fluroxypyr application to railway tracks and to elucidate some of the factors that control its environmental fate. In laboratory studies, we examined the degradation of fluroxypyr and the formation of its metabolites fluroxypyr-methoxypyridine (F-MP) and fluroxypyr-pyridinol (F-P) in soil from two Swedish railways. We also investigated the degradation and leaching of fluroxypyr in three different railway plots treated with fluroxypyr (360 g at ha(-1)). The half-life of fluroxypyr in soil samples ranged between 28 and 78 d. An estimated mean 48.6 +/- 20% of the fluroxypyr was converted into F-P and 8.0 +/- 2% into F-MP. The main metabolite, F-P, was rapidly degraded, with an average half-life of 10 +/- 5 d. However, F-MP was not degraded to a significant degree in any sample, resulting in slowly increasing concentrations throughout the experiment. This pattern of relatively rapid degradation of F-P and slow accumulation of F-MP was also observed in the field. The persistent nature of F-MP may be of concern if fluroxypyr is used repeatedly at the same location. Fluroxypyr was detected in the groundwater beneath the track at all three locations studied in concentrations exceeding the EU limit of 0.1 mu g L-1 for pesticides in drinking water, and F-P was detected in the groundwater at two of three locations. The most important factor controlling fluroxypyr degradation rate in soil was the soil water content, which modulated microbial activity and presumably also fluroxypyr availability to microorganisms. Our findings imply that fluroxypyr may not be a suitable herbicide for weed control on railway tracks.
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| 7. |
- Cederlund, Harald, et al.
(författare)
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Effect of Biochar Amendment and Ageing on Adsorption and Degradation of Two Herbicides
- 2017
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Ingår i: Water, Air, and Soil Pollution. - : Springer Science and Business Media LLC. - 0049-6979 .- 1573-2932. ; 228
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Tidskriftsartikel (refereegranskat)abstract
- Biochar amendment can alter soil properties, for instance, the ability to adsorb and degrade different chemicals. However, ageing of the biochar, due to processes occurring in the soil over time, can influence such biochar-mediated effects. This study examined how biochar affected adsorption and degradation of two herbicides, glyphosate (N-(phosphonomethyl)-glycine) and diuron (3-(3,4- dichlorophenyl)-1,1-dimethylurea) in soil and how these effects were modulated by ageing of the biochar. One sandy and one clayey soil that had been freshly amended with a wood-based biochar (0, 1, 10, 20 and 30% w/w) were studied. An ageing experiment, in which the soil-biochar mixtures were aged for 3.5 months in the laboratory, was also performed. Adsorption and degradation were studied in these soil and soil-biochar mixtures, and compared to results from a soil historically enriched with charcoal. Biochar amendment increased the pH in both soils and increased the water- holding capacity of the sandy soil. Adsorption of diuron was enhanced by biochar amendment in both soils, while glyphosate adsorption was decreased in the sandy soil. Ageing of soil-biochar mixtures decreased adsorption of both herbicides in comparison with freshly biochar-amended soil. Herbicide degradation rates were not consistently affected by biochar amendment or ageing in any of the soils. However, glyphosate half-lives correlated with the Freundlich Kf values in the clayey soil, indicating that degradation was limited by availability there.
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| 8. |
- Cederlund, Harald, et al.
(författare)
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Effects of a wood-based biochar on the leaching of pesticides chlorpyrifos, diuron, glyphosate and MCPA
- 2017
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Ingår i: Journal of Environmental Management. - : Elsevier BV. - 0301-4797 .- 1095-8630. ; 191, s. 28-34
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Tidskriftsartikel (refereegranskat)abstract
- We studied the ability of a wood-based biochar to reduce the leaching of the pesticides chlorpyrifos, diuron, glyphosate and MCPA in a sand column test system. In addition, time-dependent adsorption of the pesticides to the biochar and to the sand used in the columns was determined. The sorption kinetics was shown to be controlled by the log K-ow-values of the pesticides and sorption rates varied in the order: chlorpyrifos (log K-ow = 4.7) > diuron (log K-ow = 2.87) > MCPA (log K-ow = -0.8) > glyphosate (log K-ow = -3.2). Glyphosate sorbed very weakly to the biochar but strongly to the sand. Biochar was most effective at retaining the pesticides if applied as a distinct layer rather than mixed with the sand. Leaching of diuron and MCPA was reduced by biochar application, and the retention was linearly related to the thickness of the biochar layers. However, leaching of chlorpyrifos and glyphosate was not affected by biochar addition. Leaching was low for all pesticides when the pesticides were added directly to biochar that was then added to the column. Together, our results suggest that a viable strategy for using biochar as a means to mitigate leaching of pesticides may be to use it as an adsorptive layer directly on or close to the soil surface. This would be especially useful in areas where pesticides are routinely handled and potentially spilled. (C) 2017 Elsevier Ltd. All rights reserved.
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| 9. |
- Cederlund, Harald
(författare)
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Effects of spray drift of glyphosate on nontarget terrestrial plants – A critical review
- 2017
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Ingår i: Environmental Toxicology and Chemistry. - : Wiley. - 0730-7268 .- 1552-8618. ; 36, s. 2879-2886
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Forskningsöversikt (refereegranskat)abstract
- Glyphosate is a widely used broad-spectrum postemergent herbicide used for weed control in both agricultural and nonagricultural settings. Spray drift of glyphosate can pose a risk to nontarget terrestrial plants and plant communities outside the intended area of application, but the lack of a well-established predicted-no-effect drift rate makes properly assessing such risk difficult. For this reason, a literature review and meta-analysis was carried out with the aim to determine the level of drift that is likely to cause harm to plants and to explore what spray-reducing targets would be sufficiently protective. No-observed-adverse effect rates, lowest-observed-adverse effect rates, and effect rates giving 10, 25, and 50% effects were extracted from a total of 39 different publications. The data were combined per species, and species sensitivity distributions were constructed and fitted with a log-logistic model to assess protectiveness. No systematic differences were detected between the responses of monocotyledons or dicotyledons, but wild plants were found to be generally less sensitive to glyphosate drift than domesticated plants. The results indicate that restricting spray drift to a level below 5g a.e./ha would protect approximately 95% of all higher plant species against minor adverse effects of glyphosate drift and that rates below 1 to 2g a.e./ha would be almost completely protective. No studies were encountered that evaluated effects of spray drift against nonvascular plants, and therefore, the conclusions are only valid for vascular plants. Environ Toxicol Chem 2017;36:2879-2886. (c) 2017 SETAC
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| 10. |
- Cederlund, Harald
(författare)
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Environmental fate of glyphosate used on Swedish railways — Results from environmental monitoring conducted between 2007–2010 and 2015–2019
- 2022
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 811
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Tidskriftsartikel (refereegranskat)abstract
- Glyphosate herbicides are widely relied upon by European railway operators for controlling vegetation growing on railway tracks. In Sweden, concentrations of glyphosate and its main degradation product AMPA have been monitored in the groundwater close to railways during two monitoring periods: between 2007–2010 and 2015–2019. In total, 603 groundwater samples from 12 different monitoring sites and 645 soil samples from 5 of these sites were analyzed. Glyphosate and AMPA were detected in 16% and 14%, respectively, of groundwater samples taken from directly beneath the track, with concentrations exceeding the EU groundwater quality standard of 0.1 μg/L in 6 and 4% of the cases, respectively. The highest concentrations detected in single samples were 7 μg glyphosate/L and 1.1 μg AMPA/L. However, further horizontal spread in the groundwater zone appeared to be limited as glyphosate and AMPA were only detected in 1–3% of the groundwater samples taken from outside the track area itself, and since no difference was seen between water from reference and down-gradient wells. In the autumn of 2018, higher concentrations were detected in the groundwater from beneath 3 out of the 5 then active monitoring sites and a possible explanation is that the unusually hot and dry summer of 2018 limited degradation, thus leading to an increased susceptibility of leaching. The contents of glyphosate and AMPA in soil samples from three of the sites were very low (average < 0.05 mg/kg in soil from 0 to 30 cm), indicating that they were only sprayed to a limited degree, whereas the contents from two of the test sites were in line with what would be expected based on the used dose and a predicted half-life of about 4 ± 2 months (average 0.22–0.84 mg/kg). No signs of accumulation of glyphosate in the railway ballast over time were observed.
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| 11. |
- Cederlund, Harald, et al.
(författare)
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Hot foam for weed control-Do alkyl polyglucoside surfactants used as foaming agents affect the mobility of organic contaminants in soil?
- 2016
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Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 0304-3894 .- 1873-3336. ; 314, s. 312-317
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Tidskriftsartikel (refereegranskat)abstract
- Use of alkyl polyglucosides (APGs) as a foaming agent during hot water weed control may influence the environmental fate of organic contaminants in soil. We studied the effects of the APG-based foaming agent NCC Spuma (C8-C10) on leaching of diuron, glyphosate, and polycyclic aromatic hydrocarbons (PAHs) in sand columns. We also examined how APG concentration affected the apparent water solubility and adsorption of the herbicides and of the PAHs acenaphthene, acenaphthylene and fluorene. Application of APGs at the recommended concentration of 0.3% did not significantly affect leaching of any of the compounds studied. However, at a concentration of 1.5%, leaching of both diuron and glyphosate was significantly increased. The increased leaching corresponded to an increase in apparent water solubility of diuron and a decrease in glyphosate adsorption to the sand. However, APG addition did not significantly affect the mobility of PAHs even though their apparent water solubility was increased. These results suggest that application of APG-based foam during hot water weed control does not significantly affect the mobility of organic contaminants in soil if used according to recommendations. Moreover, they suggest that APGs could be useful for soil bioremediation purposes if higher concentrations are used.
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| 12. |
- Cederlund, Harald
(författare)
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Koll på miljökontrollen – en sammanställning av resultaten från det nationella miljökontrollprogrammet för kemisk ogräsbekämpning på järnväg 2006–2019
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Den här rapporten sammanställer resultaten från de miljökontrollprogram för kemisk ogräsbekämpning på järnväg som har bedrivits på uppdrag av Banverket och Trafikverket mellan åren 2006–2010 (period 1) och 2015–2019 (period 2). Inom ramen för miljökontrollprogrammen har koncentrationen av glyfosat och dess nedbrytningsprodukt AMPA analyserats i grundvatten från provtagningsrör installerade i eller vid sidan av järnvägen och under period 2 även halten glyfosat och AMPA i jordprover som tagits i närheten av rören. Totalt har strax över 600 grundvattenprover analyserats från 12 olika provplatser utspridda över landet och 645 jordprover från fem av dessa provplatser. Glyfosat och AMPA detekterades i 16% respektive 14% av de grundvattenprover som tagits från provtagningsrör som installerats i själva spårområdet. De högsta koncentrationerna som uppmätts i några enskilda prover var 7 μg glyfosat/l respektive 1,1 μg AMPA/l i grundvatten direkt under spåret. Dessa värden är dock knappast representativa för hela datasetet vilket illustreras av att de 95:e percentilerna för grundvatten under spåret var 0,15 μg glyfosat/l och 0,037 μg AMPA/l. Spridningen till omgivningen tycks också vara relativt begränsad, glyfosat och AMPA detekterades bara i 1–3% av proverna som tagits i grundvattenrör utanför spårområdet. 2018 avviker som ett år med ovanligt förhöjda koncentrationer detekterade i grundvattnet under flera av provplatserna vilket förmodligen hänger samman med den ovanligt torra sommaren det året. Halterna i jordprover från tre av provplatserna var väldigt låga vilket indikerar att de endast har bekämpats i begränsad utsträckning (period 2) medan halterna för de två övriga platserna är rimliga utifrån den använda dosen och en förväntad halveringstid på 4 ± 2 månader. Rapporten diskuterar hur resultaten ska tolkas, hur miljökontrollprogrammet har bedrivits och hur det kan utvecklas framöver.
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| 13. |
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| 14. |
- Cederlund, Harald
(författare)
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Ogräsbekämpning med hetvattenskum : resultat från en fältstudie på en av järnvägens driftplatser
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Som en del i arbetet att utvärdera alternativ till kemiska bekämpningsmedel för ogräsbekämpning i järnvägsmiljöer utfördes under sommaren 2014 ett test med hetvattenskum på en bangård i Kristianstad. Den här rapporten presenterar resultat från fältförsöket och innehåller också en sammanställning av kunskapsläget kring ogräsbekämpning med hetvattenskum och dess miljöpåverkan. Ogräsbekämpning med hetvattenskum är en termisk metod som dödar ogräsen genom att denaturera proteiner och förstöra cellstrukturer. Skummet, vars funktion är att bilda ett isolerande skikt så att mer energi kan överföras till växten, består av biologiskt nedbrytbara alkylpolyglykosider. Behandlingen med hetvattenskum gav en tydlig men relativt kortvarig minskning av ogräsens täckningsgrad på behandlade ytor men behöver upprepas under växtsäsongen för att förhindra att ogräs återväxer från överlevande rötter och att nya ogräs etablerar sig efter utförd bekämpning. Även en enkel behandling med hetvattenskum kan dock ge skillnader i hur högväxande ogräsen blir och i vilken utsträckning de går i blom som kvarstår under större delen av sommaren. Litteraturstudien indikerade att den största miljöpåverkan från hetvattensbekämpningen uppstår i samband med uppvärmningen av preparatet. En rekommendation är därför att i samband med framtida användning ålägga entreprenören att redovisa data över vatten-, bränsleförbrukning och bekämpad areal i form av dagrapporter för att bättre kunna bedöma hur stor denna påverkan är. Bekämpning med hetvattenskum är dyrare än kemisk ogräsbekämpning men framstår ändå som ett intressant alternativ för ytor där användningen av kemiska bekämpningsmedel inte är tillåten.
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| 15. |
- Cederlund, Harald
(författare)
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Overcoming biochar limitations to remediate pentachlorophenol in soil by modifying its electrochemical properties
- 2022
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Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 0304-3894 .- 1873-3336. ; 426
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we produced modified biochars with enhanced electrochemical properties to increase PCP remediation in soil. Although all biochars enhanced PCP remediation in aerobic conditions, only a few did in anaerobic soil. The most successful modifications were (i) the preloading of biomass with 10% w/w FeCl3, to obtain a biochar rich in redox-active metals (B-Fe); (ii) the oxidation of a conductive biochar pyrolyzed at 1000 ºC with 0.025 M KMnO4, to produce a biochar with both moderate conductivity and redox capacity (B-1000-KMnO4); and (iii) KMnO4 oxidation of an amorphous biochar pyrolyzed at 400 ºC to obtain a biochar with very high redox capacity (B-KMnO4). B-Fe reduced extractable PCP to almost zero after 50 days in both incubations, but showed slow kinetics of remediation in aerobic soil. B-1000-KMnO4 had the highest rate of remediation under aerobic conditions, but no significant effect under anaerobic conditions. B-KMnO4, however, presented high rates of remediation and high removal of extractable PCP under both conditions, which made it the recommended modification strategy for increased PCP remediation. We found that the degree of remediation primarily depends on the redox capacity, while the rate of remediation was determined by both the conductivity and redox capacity of biochar.
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| 16. |
- Cederlund, Harald
(författare)
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Riskkarakterisering av oavsiktlig spridning av glyfosat vid ogräsbekämpning på järnväg
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I den här rapporten undersöks riskerna med oavsiktlig spridning av glyfosat, via vindavdrift eller utlakning, när glyfosatpreparat används för ogräsbekämpning på järnväg. Syftet med arbetet har varit att ta fram ett underlag som kan användas för att besluta om vilka skyddsavstånd som i normalfallet krävs till olika typer av käns-liga områden som omger järnvägen. Så kallade riskkarakteriseringskvoter har räk-nats fram genom att jämföra förutspådda miljökoncentrationer (PEC-värden) med förutspådda koncentrationer utan effekt (PNEC-värden). Beräkningarna visar att riskerna med mänsklig exponering och spridning till ytvatten genomgående är små och relativt okänsliga för olika antaganden kring spridningens storlek. De minimi-skyddsavstånd för skydd av yt- och dricksvatten (6 och 12 m) som föreslås av Na-turvårdsverket bedöms därmed som tillräckliga. Risken för påverkan på omkring-liggande vegetation bedöms som acceptabel men då riskkarakteriseringskvoten för påverkan på vegetation ligger nära ett är den bedömningen mer känslig för vilka antaganden som görs. Då det råder vissa frågetecken rörande hur representativa de vindavdriftsmätningar som har utförts på ogräståget är för svenska förhållanden är det därför av vikt att dessa mätningar upprepas för att ge ett bättre beräkningsun-derlag. Risken att enskilda brunnar som ligger nära järnvägen kontamineras via utlakning i koncentrationer som överstiger 0,1 μg/l kan inte helt uteslutas och be-hovet av skyddsavstånd till dessa bör bedömas från fall till fall.
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| 17. |
- Cederlund, Harald, et al.
(författare)
-
Soil carbon quality and nitrogen fertilization structure bacterial communities with predictable responses of major bacterial phyla
- 2014
-
Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393 .- 1873-0272. ; 84, s. 62-68
-
Tidskriftsartikel (refereegranskat)abstract
- Agricultural practices affect the soil ecosystem in multiple ways and the soil microbial communities represent an integrated and dynamic measure of soil status. Our aim was to test whether the soil bacterial community and the relative abundance of major bacterial phyla responded predictably to long-term organic amendments representing different carbon qualities (peat and straw) in combination with nitrogen fertilization levels and if certain bacterial groups were indicative of specific treatments. We hypothesized that the long-term treatments had created distinctly different ecological niches for soil bacteria, suitable for either fast-growing copiotrophic bacteria, or slow-growing oligotrophic bacteria. Based on terminal-restriction fragment length polymorphism of the 16S rRNA genes from the total soil bacterial community and taxa-specific quantitative real-time PCR of seven different groups, all treatments significantly affected the community structure, but nitrogen fertilization was the most important driver for changes in the relative abundances of the studied taxa. According to an indicator species analysis, the changes were largely explained by the decline in the relative abundances of Acidobacteria, Gemmatimonadetes and Verrucomicrobia with nitrogen fertilization. Conditions more favourable for copiotrophic life strategies were indicated in these plots by the decreased metabolic quotient, i.e. the ratio between basal respiration rate and soil biomass. Apart from the Alphaproteobacteria that were significantly associated with peat, no taxa were indicative of organic amendment in general. However, several significant indicators of both peat and straw were identified among the terminal restriction fragments suggesting that changes induced by the organic amendments were mainly manifested at a lower taxonomical level. Our findings strengthen the proposition that certain higher bacterial taxa adapt in an ecologically coherent way in response to changes induced by fertilization. (C) 2014 Elsevier B.V. All rights reserved.
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| 18. |
- Cederlund, Harald
(författare)
-
Studier av ogräsbekämpning på banvallar 2006-2015 : resultat och slutsatser från 10 års tillämpad forskning
- 2016
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Den här rapporten beskriver och sammanfattar resultaten från den forskning som på uppdrag av Banverket och Trafikverket har bedrivits mellan 2006-2015 med syfte att utvärdera metoder för ogräsbekämpning på svenska järnvägar. Som en bakgrund ges såväl en historisk överblick som en översikt över hur ogräsbekämpning utförs på svenska järnvägar idag. I bakgrundsavsnittet sammanfattas också kortfattat den kunskap som finns rörande hur glyfosat, som är den enda aktiva beståndsdel som är godkänd för användning på järnväg i Sverige idag, verkar, bryts ned och sprids i järnvägsmiljön. Forskningen har omfattat såväl fältstudier som olika typer av labstudier och har inbegripit utvärdering av både kemiska bekämpningsmedel och alternativa metoder som bekämpning med ättika och hetvatten. Forskningen har varit inriktad på att identifiera bekämpningsmedel som skulle kunna ersätta eller användas som blandningspartner till glyfosat för att bredda effekten eller för att förebygga resistensutveckling hos ogräsen. Det har dock visat sig svårt att identifiera metoder som är tillräckligt effektiva och samtidigt inte är alltför utlakningskänsliga. Substanser som karfentrazonetyl och flazasulfuron skulle kunna utgöra framtida blandningspartners till glyfosat men deras nedbrytning i banvallen är än så länge otillräckligt studerad. Bekämpning med hetvattenskum skulle kunna utgöra en alternativ metod för vissa mindre områden där kemisk bekämpning är otillåten men är knappast användbar i större skala. I rapporten rekommenderas Trafikverket att på ett mer systematiskt sätt mäta ogräsförekomst och utvärdera bekämpningens effektivitet, att undersöka om anläggning av gröna spår, dvs. spår med lågväxande vegetation, skulle kunna ersätta ogräsbekämpning på vissa stadsnära sträckor samt att arbeta fram en långsiktig strategi för hur man vill utveckla sättet som ogräsbekämpning bedrivs på.
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| 19. |
- Cederlund, Harald, et al.
(författare)
-
Utveckling av metod för att bedöma behovet av ogräsbekämpning i spår
- 2014
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A system for weed management on railway embankments that is both adapted to the environment and efficient in terms of resources requires knowledge and understanding about the growing conditions of vegetation so that methods to control its growth can be adapted accordingly. Automated records could complement present-day manual inspections and over time come to replace these. One challenge is to devise a method that will result in a reasonable breakdown of gathered information that can be managed rationally by affected parties and, at the same time, serve as a basis for decisions with sufficient precision. The project examined two automated methods that may be useful for the Swedish Transport Administration in the future: 1) A machine vision method, which makes use of camera sensors as a way of sensing the environment in the visible and near infrared spectrum; and 2) An N-Sensor method, which transmits light within an area that is reflected by the chlorophyll in the plants. The amount of chlorophyll provides a value that can be correlated with the biomass. The choice of technique depends on how the information is to be used. If the purpose is to form a general picture of the growth of vegetation on railway embankments as a way to plan for maintenance measures, then the N-Sensor technique may be the right choice. If the plan is to form a general picture as well as monitor and survey current and exact vegetation status on the surface over time as a way to fight specific vegetation with the correct means, then the machine vision method is the better of the two. Both techniques involve registering data using GPS positioning. In the future, it will be possible to store this information in databases that are directly accessible to stakeholders online during or in conjunction with measures to deal with the vegetation. The two techniques were compared with manual (visual) estimations as to the levels of vegetation growth. The observers (raters) visual estimation of weed coverage (%) differed statistically from person to person. In terms of estimating the frequency (number) of woody plants (trees and bushes) in the test areas, the observers were generally in agreement. The same person is often consistent in his or her estimation: it is the comparison with the estimations of others that can lead to misleading results. The system for using the information about vegetation growth requires development. The threshold for the amount of weeds that can be tolerated in different track types is an important component in such a system. The classification system must be capable of dealing with the demands placed on it so as to ensure the quality of the track and other pre-conditions such as traffic levels, conditions pertaining to track location, and the characteristics of the vegetation. The project recommends that the Swedish Transport Administration: Discusses how threshold values for the growth of vegetation on railway embankments can be determined Carries out registration of the growth of vegetation over longer and a larger number of railway sections using one or more of the methods studied in the project Introduces a system that effectively matches the information about vegetation to its position Includes information about the growth of vegetation in the records that are currently maintained of the track’s technical quality, and link the data material to other maintenance-related databases Establishes a number of representative surfaces in which weed inventories (by measuring) are regularly conducted, as a means of developing an overview of the long-term development that can serve as a basis for more precise prognoses in terms of vegetation growth Ensures that necessary opportunities for education are put in place
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| 20. |
- Cederlund, Harald, et al.
(författare)
-
Utveckling av metod för att bedöma behovet av ogräsbekämpning i spår
- 2014
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- En miljöanpassad och resurseffektiv hantering av ogräs i spår ställer krav på god kunskap om vegetationsförhållanden för att behovsanpassa bekämpningsinsatserna. En automatiserad registrering skulle kunna utgöra ett komplement till dagens manuella inspektioner och skulle över tiden helt eller delvis kunna ersätta dessa. En utmaning är att hitta en metod som ger en rimlig upplösning i informationen som samlas in, så att den kan hanteras rationellt av berörda aktörer och samtidigt utgöra ett beslutsunderlag med tillräcklig precision. Projektet studerade två automatiserade metoder som kan vara aktuella för Trafikverket att använda i framtiden: 1) Machine vision metoden utnyttjar kamerasensorer för att känna av sin omgivning i det synliga respektive nära infraröda spektrumet. 2) N-sensorn sänder ut ljus inom det område som reflekteras av växternas klorofyll. Mängden klorofyll ger ett mätvärde som kan korreleras till biomassan. Valet av teknik beror på vad informationen ska användas till. Om syftet är att översiktligt kartlägga vegetationsförekomst i spår, för att planera åtgärder för underhåll, kan N-sensortekniken vara lämplig. Om man över ytan och tiden vill övervaka och kartlägga aktuell och precis vegetationsstatus, för att kunna bekämpa utvald vegetation med rätt insats, är machine vision tekniken bättre lämpad. Såväl machine vision metoden som N-sensortekniken bygger på registrering av data tillsammans med en GPS-positionering. På sikt kan denna information läggas i databaser som är direkt åtkomliga för berörda organisationer och t o m online i fält under eller i samband med en bekämpningsåtgärd. De två teknikerna jämfördes med manuella (visuella) skattningar av ogräsförekomsten. Den visuella skattningen av yttäckningsgrad av ogräs i fält skiljde sig statistiskt mellan olika bedömare. När det gäller att uppskatta frekvensen (antalet) vedartade växter (träd och buskar) inom provytorna så var observatörerna relativt överens. Samma person är ofta konsekvent i sitt bedömande, men att jämföra med andra personers bedömning kan ge missvisande resultat. Systemet för användning av informationen om ogräsförekomst behöver utvecklas som helhet. Tröskelvärden för hur mycket ogräs som kan tolereras på olika typer av spår/driftsplatser är en viktig komponent i ett sådant system. Klassificeringssystemet ska kunna hantera de krav som ställs för att säkerställa banans kvalitet och olika förutsättningar som trafikförhållanden, platsgivna förutsättningar för banan och vegetationens egenskaper. Projektet rekommenderar Trafikverket att: diskutera hur tröskelvärden för vegetationsförekomst på spår kan fastställas genomföra registrering av vegetationsförekomst över längre och fler sträckor med en eller flera av de metoder som studerats i projektet inleda införande av system som effektivt kopplar informationen om vegetation till position inkludera förekomst av vegetation i den registrering som idag sker av spårens (banans) tekniska kvalitet och ansluta datamaterialet till övriga underhållsrelaterade databaser inrätta ett antal representativa ytor där ogräsfloran på spåren regelbundet inventeras och mäts för att få en bild av den långsiktiga utveckling som grund för säkrare prognoser för vegetationsutveckling säkerställa att nödvändiga utbildningsinsatser genomförs
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| 21. |
- Cederlund, Harald
(författare)
-
Utveckling av metoder för vegetationsbekämpning i järnvägsmiljö : redovisning av genomförda aktiviteter 2019–2021 samt förslag på fortsatt verksamhet
- 2021
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Trafikverket bekämpar regelbundet ogräsen på banvallen för att säkra en god bankvalitet. Ett återkommande problem är svårigheten att veta hur stort behovet av bekämpning är, vilka bansträckor som skall prioriteras och vilken teknik som skall användas för bekämpningen. Ogräsbekämpningen sker idag främst kemiskt med glyfosatpreparat. Det är dock av flera anledningar osäkert hur länge glyfosat kommer att finnas tillgängligt för Trafikverket och bekämpningsbehovet måste i alla händelser lösas även för så kallade restriktionsytor dvs. sträckor som ej får bekämpas kemiskt, som finns bl.a. vid vattenskyddsområden och vattendrag. Trots att ett flertal metoder för icke-kemisk vegetationsbekämpning studerats de senast 25 åren finns det fortfarande få etablerade metoder och tekniska lösningar som kommit till större användning. Det finns således ett fortsatt behov av att prova icke-kemiska metoder i praktisk drift i samarbete med Trafikverket och entreprenörer samt ta fram bättre underlag – handböcker – för att de icke-kemiska metoderna ska komma till praktisk användning. Inom projektet har två redskap – en uppryckningsgrip och en kratta/skrapa – utvecklats och provats i spår. En nygammal metod för rensning och profilering av banketten - ballastplogning – har testats med äldre utrustning. Demonstrationsytor där de olika metoderna utvärderas i full skala, har anlagts på bandel 371 MoraÄlvdalen. I samma fältförsök utvärderas också ett system för gröna spärrzoner som syftar till att minska sannolikheten att aggressiv vegetation växer in i spår från angränsande ytor. Inledande försök och teknikutveckling för användning av ånga och hetvatten har också påbörjats. Det finns också ett allt större behov av bättre metoder för att styra och utvärdera bekämpningsinsatserna (oavsett metod) samt att kunna bedöma hur den utförda bekämpningen långsiktigt påverkar såväl ogräsen som banan. Inom projektet utnyttjas högupplöst data över ogräsförekomster på järnvägen och data över utförda kemiska bekämpningar som samlats in under de senaste åren för att undersöka hur tillståndet utvecklas långsiktigt, undersöka effektsamband och ta fram bättre planeringsverktyg för ogräsbekämpningen. Vindavdrift från ogräsbekämpningståget har uppmätts i 4 olika fältförsök utförda på 3 olika bandelar. Resultaten visar att på 1 m avstånd från det besprutade områdets gräns så har den deponerade mängden minskat till i genomsnitt 0,3 0,2 % av den använda dosen, motsvarande 5 4 g/ha med den föreskrivna dosen på 1800 g glyfosat/ha. Resultaten kommer att användas för att göra en uppdaterad riskkarakterisering. Projektet löper även under 2021 och planering för fortsatt verksamhet därefter har inletts.
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| 22. |
|
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| 23. |
- Cederlund, Harald, et al.
(författare)
-
Utveckling av metoder för vegetationsbekämpning i järnvägsmiljö -redovisning av genomförda och pågående aktiviteter 2019–2020
- 2021
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Trafikverket bekämpar regelbundet ogräsen på banvallen för att säkra en god bankvalitet. Ett återkommande problem är svårigheten att veta hur stort behovet av bekämpning är, vilka bansträckor som skall prioriteras och vilken teknik som skall användas för bekämpningen. Ogräsbekämpningen sker idag främst kemiskt med glyfosatpreparat. Det är dock av flera anledningar osäkert hur länge glyfosat kommer att finnas tillgängligt för Trafikverket och bekämpningsbehovet måste i alla händelser lösas även för så kallade restriktionsytor dvs. sträckor som ej får bekämpas kemiskt, som finns bl.a. vid vattenskyddsområden och vattendrag. Trots att ett flertal metoder för icke-kemisk vegetationsbekämpning studerats de senast 25 åren finns det fortfarande få etablerade metoder och tekniska lösningar som kommit till större användning. Det finns således ett fortsatt behov av att prova icke-kemiska metoder i praktisk drift i samarbete med Trafikverket och entreprenörer samt ta fram bättre underlag – handböcker – för att de icke-kemiska metoderna ska komma till praktisk användning. Inom projektet har två redskap – en uppryckningsgrip och en kratta/skrapa – utvecklats och provats i spår. En nygammal metod för rensning och profilering av banketten - ballastplogning – har testats med äldre utrustning. Demonstrationsytor där de olika metoderna utvärderas i full skala, har anlagts på bandel 371 MoraÄlvdalen. I samma fältförsök utvärderas också ett system för gröna spärrzoner som syftar till att minska sannolikheten att aggressiv vegetation växer in i spår från angränsande ytor. Inledande försök och teknikutveckling för användning av ånga och hetvatten har också påbörjats. Det finns också ett allt större behov av bättre metoder för att styra och utvärdera bekämpningsinsatserna (oavsett metod) samt att kunna bedöma hur den utförda bekämpningen långsiktigt påverkar såväl ogräsen som banan. Inom projektet utnyttjas högupplöst data över ogräsförekomster på järnvägen och data över utförda kemiska bekämpningar som samlats in under de senaste åren för att undersöka hur tillståndet utvecklas långsiktigt, undersöka effektsamband och ta fram bättre planeringsverktyg för ogräsbekämpningen. Vindavdrift från ogräsbekämpningståget har uppmätts i 4 olika fältförsök utförda på 3 olika bandelar. Resultaten visar att på 1 m avstånd från det besprutade områdets gräns så har den deponerade mängden minskat till i genomsnitt 0,3 0,2 % av den använda dosen, motsvarande 5 4 g/ha med den föreskrivna dosen på 1800 g glyfosat/ha. Resultaten kommer att användas för att göra en uppdaterad riskkarakterisering. Projektet löper även under 2021 och planering för fortsatt verksamhet därefter har inletts.
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| 24. |
- Riddle, Matthew, et al.
(författare)
-
Impact of biochar coated with magnesium (hydr)oxide on phosphorus leaching from organic and mineral soils
- 2019
-
Ingår i: Journal of Soils and Sediments. - : Springer Science and Business Media LLC. - 1439-0108 .- 1614-7480. ; 19, s. 1875-1889
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose Recent research suggests that Swedish organic arable soils have been under-recognized as a potential source of phosphorus (P) loading to water bodies. The aim of this study was to compare P losses through leaching from organic and high-fertility mineral soils. In addition, the effectiveness of a magnesium-salt-coated biochar applied below the topsoil as a mitigation strategy for reducing P losses was evaluated.Materials and methods Phosphorus leaching was measured from four medium- to high-P arable soils, two Typic Haplosaprists (organic 1 and 2), a Typic Hapludalf (sand), and an unclassified loam textured soil (loam), in a 17-month field study utilizing 90-cm-long lysimeters. A magnesium-salt-coated biochar was produced and characterized using X-ray powder diffraction (XPD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), and X-ray adsorption (XANES) spectroscopy, and its phosphate adsorption capacity was determined at laboratory scale. It was also applied as a 3-cm layer, 27 cm below the soil surface of the same lysimeters and examined as a mitigation measure to reduce P leaching.Results and discussion Total-P loads from the 17-month, unamended lysimeters were in the order of organic 2 (1.2kgha(-1))>organic 1 (1.0 kgha(-1))>sand (0.3 kgha(-1))>loam (0.2 kgha(-1)). Macropore flow, humic matter competition for sorption sites, and fewer sorption sites likely caused higher P losses from the organic soils. Analysis by XRD and SEM revealed magnesium was primarily deposited as periclase (MgO) on the biochar surface but hydrated to brucite (Mg(OH)(2)) in water. The Langmuir maximum adsorption capacity (Q(max))of the coated biochar was 65.4 mg Pg(-1). Lysimeters produced mixed results, with a 74% (P<0.05), 51% (NS), and 30% (NS) reduction in phosphate-P from the organic 1, organic 2, and sand, respectively, while P leaching increased by 230% (NS) from the loam.Conclusions The findings of this study indicate that P leached from organic arable soils can be greater than from mineral soils, and therefore, these organic soils require further investigation into reducing their P losses. Metal-enriched biochar, applied as an adsorptive layer below the topsoil, has the potential to reduce P losses from medium- to high-P organic soils but appear to be less useful in mineral soils.
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| 25. |
- Riddle, Matthew, et al.
(författare)
-
Magnetite-coated biochar as a soil phosphate filter: From laboratory to field lysimeter
- 2018
-
Ingår i: Geoderma. - : Elsevier BV. - 0016-7061 .- 1872-6259. ; 327, s. 45-54
-
Tidskriftsartikel (refereegranskat)abstract
- Agriculture is one of the largest anthropogenic contributors of phosphorus (P) to surface waters and reducing these P loads is a target set by many countries. One potential mitigation strategy could be to utilize biochar, functionalized by co-precipitating metal ions onto its surface to adsorb phosphates. We evaluated such an approach in a series of laboratory experiments and a three-year field lysimeter study. Leached phosphates were trapped in a 3-cm layer of a commercially available 20% hardwood/80% Norway spruce biochar, coated with magnetite and placed under the soil root zone. Langmuir maximum adsorption potential (Qmax) was 3.38 mg P g(-1) biochar, as determined from batch adsorption studies performed at pH 6.5. Further laboratory experiments revealed that adsorption was strongly negatively correlated with pH (R-2 = 0.995). In a laboratory column study using high flow rates, no difference was found in phosphate adsorption between coated biochar and the control (no biochar), after application of ammonium phosphate at a rate corresponding to 22 kg P ha(-1). However, differences were observed at higher application rates (285 or 570 kg P ha(-1)). Calculation of a Fe:P molar ratio to evaluate the magnetite treatment method from laboratory (2:1) to lysimeter (248:1) suggested a relatively effective laboratory performance, but overall poor field efficiency. Nevertheless, biochar in the lysimeter study still reduced phosphate leaching from two organic soils, by 62% (P < 0.05) and 35% (NS). This suggests that, even though the method of magnetite-coating biochar is not necessarily resource-efficient, it is effective in removing P from soil leachate.
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| 26. |
- Risberg, Kajsa, et al.
(författare)
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Comparative characterization of digestate versus pig slurry and cow manure - Chemical composition and effects on soil microbial activity
- 2017
-
Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 61, s. 529-538
-
Tidskriftsartikel (refereegranskat)abstract
- The growing number of biogas plants in Europe has resulted in increased production of nutrient-rich digestate with great potential as fertilizer for arable land. The nutrient composition of digestate varies with the substrate treated in the biogas plant and may contain compounds that stimulate or inhibit soil microbial activity. This study compared 20 digestates (D) with 10 pig slurries (PS) and 10 cow manures (CM) regarding their chemical content and their effect on soil microbial activities, i.e. potential ammonia oxidation rate (PAO) and soil respiration. The results showed no significant differences within the D group when divided based on substrate type. i.e. manure dominated vs. other organic waste materials in any of the tests. In general D contained significantly higher concentrations of ammonium while the concentrations of total carbon and volatile fatty acids were higher in PS and CM than in D. The D showed both stimulating and inhibiting effects on PAO, while all CM and all PS except one showed inhibiting effects on PAO. However, PAO activity was negatively correlated with the content of volatile fatty acids in the residues indicating that these compounds may be the cause of the inhibition. The maximum respiration activity (hpeakmax) was lower and the time point for the maximum respiration activity (t(peakmax))occurred earlier for D compared with CM and PS. This earlier peak time could be indicative of a high proportion of easily degradable carbon in D compared with PS and CM. However, the utilization rate of carbon, i.e. the proportion of added organic C converted to CO2-C during 12 days, did not differ significantly between D, PS and CM, indicating that overall carbon quality in the different fertilizers was still roughly comparable. In short, our results suggest that digestates were different compared with PS and CM but without posing a higher risk with respect to their impact on soil microbial activity. (C) 2016 The Author(s). Published by Elsevier Ltd.
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