| 1. |
- Gilles, Stefanie, et al.
(författare)
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Pollen exposure weakens innate defense against respiratory viruses.
- 2020
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Ingår i: Allergy. - : Wiley. - 1398-9995 .- 0105-4538. ; 75:3, s. 576-587
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Tidskriftsartikel (refereegranskat)abstract
- Hundreds of plant species release their pollen into the air every year during early spring. During that period, pollen allergic as well as non-allergic patients frequently present to doctors with severe respiratory tract infections.To assess whether pollen may interfere with antiviral immunity.We combined data from real life human exposure cohorts, a mouse model and human cell culture to test our hypothesis.Pollen significantly diminished interferon-λ and pro-inflammatory chemokine responses of airway epithelia to rhinovirus and viral mimics and decreased nuclear translocation of interferon regulatory factors. In mice infected with respiratory syncytial virus, co-exposure to pollen caused attenuated antiviral gene expression and increased pulmonary viral titers. In non-allergic human volunteers, nasal symptoms were positively correlated with airborne birch pollen abundance, and nasal birch pollen challenge led to down-regulation of type I and -III interferons in nasal mucosa. In a large patient cohort, numbers of rhinovirus-positive cases were correlated with airborne birch pollen concentrations.The ability of pollen to suppress innate antiviral immunity, independent of allergy, suggests that high-risk population groups should avoid extensive outdoor activities when pollen and respiratory virus seasons coincide.
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| 2. |
- Sternbeck, John, et al.
(författare)
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Miljökontroll av omgivningspåverkan vid efterbehandlingsåtgärder
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Miljökontroll av omgivningspåverkan används för att kontrollera konsekvenser av utsläpp från en verksamhet eller ett förorenat område. Miljökontroll kan även användas för att påvisa förändringar över tid, t.ex. vid bedömning av måluppfyllelsen av en efterbehandlingsåtgärd eller vid diffus antropogen påverkan. För att miljökontroll på ett effektivt sätt ska kunna besvara dessa frågor krävs en sammanhållen strategi, med särskild tonvikt på målformulering. Här presenteras en strategi för miljökontroll av omgivningspåverkan från ett enskilt förorenat objekt, där föroreningskällan kan vara jord, sediment eller grundvatten. Strategin omfattar syfte, mätprogram, kontrollmål, tidsplan, utvärdering och åtgärdsplan. Kontrollprogrammet för ett efterbehandlingsobjekt ska utgå från föregående riskbedömning, åtgärdsutredning och riskvärdering. Kontrollen indelas i tre faser: 1) före, 2) under, och 3) efter åtgärd. Mätningar under fas 1 är väsentligt för att kunna bedöma förändringar över tid. Kontrollmål ska vara kvantitativa och kunna följas upp genom mätningar. Överskridanden av kontrollmål ska motsvaras av en åtgärdsplan. I rapporten redovisas hur kontrollmål kan utformas för att bedöma: • Risk • Ekologisk status • Tillfälliga avvikelser • Långsiktiga förändringar I rapporten ges förslag på enkla metoder för att bedöma tillfälliga avvikelser och långsiktiga förändringar, både för normalfördelade och log-normalfördelade data. För att beräkna dessa kontrollmål krävs kännedom om halternas variabilitet. Schablonvärden för variabilitet har tagits fram för olika föroreningar i ytvatten och fisk. Efterbehandling avses ofta medföra gradvis minskande föroreningshalter i omgivningen. Genom beräkning av teststyrka visas hur länge mätningar måste pågå för att man ska kunna påvisa en statistiskt säkerställd förändring. Vi visar också hur mätseriens längd är relaterad till provtagningsfrekvens, variabiliteten i data, och förändringens storlek. Denna kunskap används vid utformning av mätprogram och upprättande av tidsplan, för att säkerställa att ett föreslaget mätprogram verkligen förmår visa det programmet syftar till att visa. Den föreslagna strategin, särskilt avseende kontrollmål och utvärdering, bör även vara tillämpbar inom andra områden än efterbehandling, t.ex. recipientkontroll, egenkontroll och lokal eller regional miljöövervakning
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| 3. |
- Sun, Xiaole, 1983-, et al.
(författare)
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Stable silicon isotope analysis on nanomole quantities using MC-ICP-MS with a hexapole gas-collision cell
- 2010
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Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 25:2, s. 156-162
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate in this study that a single focusing multiple collector inductively coupled plasma massspectrometer (MC-ICP-MS) equipped with a hexapole gas-collision cell (GV-instrument Isoprobe) canprecisely determine the d29Si (2S.D., 0.2&) using a total Si consumption of less than 14 nmole (390 ngSi). Testing and evaluation of background, rinse time, and major matrix effects have been performed ina systematic way to establish a procedure to measure d29Si in small quantities. Chemical purificationprior to analysis is required to remove potential interferences. For data collected during a four-yearperiod, the average d29Si value of IRMM-018 relative to NBS-28 was found to be 0.95& (n ¼ 23,2S.D. 0.16&) with a 95% confidence interval (0.95 0.028&). The mean d29Si value of the Big-Batchstandard was found to be 5.50& (n ¼ 6, 2S.D. 0.26&). Although determination of the d30Simeasurements is not possible, with our current instrument we demonstrate that this system providesa fast and long-term reliable method for the analysis of d29Si in purified samples with low Siconcentration (18 mM Si).
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| 4. |
- Andersson, Karolina, et al.
(författare)
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Alternativa metoder för myggbekämpning : En kunskapsöversikt
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Naturvårdsverket fick 2013 ett regeringsuppdrag att utvärdera olika effekter av biologisk bekämpning av översvämningsmyggor med VectoBac G. Som en del av uppdraget publicerade EviEM under 2015 en kunskapsöversikt om vad som är känt kring effekterna av biologisk myggbekämpning med Bti(Bacillus thuringiensis israelensis) och specifikt insekticiden VectoBac G. Regeringen gav sedan i maj 2016 Naturvårdsverket i uppdrag att bevaka forskningsläget vad gäller alternativa åtgärder för att bekämpa och minska förekomsten av översvämningsmygg. I december 2017 beslutades att EviEM på uppdrag av Naturvårdsverket ska sammanfatta det vetenskapliga kunskapsläget kring alternativa metoder för myggbekämpning, användningen av Bti exkluderat. Denna rapport redovisar och sammanfattar kunskapsläget för sex alternativa metoder för minskning och bekämpning av mygg; bete, slåtter, dikesrensning, förändrad reglering av vattenflöden, buskröjning och sterilisering av mygghanar.
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| 5. |
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| 6. |
- Envall, Ida, et al.
(författare)
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Existing evidence related to soil retention of phosphorus from on-site wastewater treatment systems in boreal and temperate climate zones : a systematic map
- 2023
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Ingår i: Environmental Evidence. - : Springer Nature. - 2047-2382. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: In Sweden there are nearly one million soil-based on-site wastewater treatment systems (OWTSs). OWTSs may contribute to eutrophication of surface waters, due to the discharge of phosphorus (P). Hence, in certain cases, a high P removal rate (up to 90%) of OWTSs is required by Swedish authorities. Since these requirements may have costly consequences to property owners, it is debated whether they are too strict. In this debate, it is often claimed that the soil retention of P occurring in the natural environments may be underestimated by authorities. Soil retention is the inhibition of the transport of P through the ground, due to different chemical, physical and biological processes occurring there. These processes make the P transport slower, which may reduce the unwanted impact on receiving water bodies. However, the efficiency of soil retention of P remains unclear. The objective of this systematic map was to collect, code, organise and elucidate the relevant evidence related to the topic, to be able to guide stakeholders through the evidence base, and to support future research synthesising, commissioning, and funding. The systematic map was carried out in response to needs declared by the Swedish Agency for Marine and Water Management but the conclusions should be valid for a wider range of countries across boreo-temperate regions.Methods: Searches were made for peer-reviewed and grey literature using bibliographic databases, search engines, specialist websites, and stakeholder contacts. The references were screened for relevance according to a predefined set of eligibility criteria. A detailed database of the relevant studies was compiled. Data and metadata that enable evaluation and discussion of the character and quality of the evidence base were extracted and coded. Special focus was placed on assessing if existing evidence could contribute to policy and practice decision making. Descriptive information about the evidence base was presented in tables and figures. An interactive evidence atlas and a choropleth were created, displaying the locations of all studies.Review findings: 234 articles out of 10,797 screened records fulfilled the eligibility criteria. These articles contain 256 studies, performed in the field or in the laboratory. Six different study types were identified, based on where the measurements were conducted. Most studies, including laboratory studies, lack replicates. Most field studies are observational case studies.Conclusions: It is not possible to derive valid generic measures of the efficiency of soil retention of P occurring in the natural soil environment from available research. Neither does the evidence base allow for answering the question of the magnitude of the potential impact of OWTSs on the P concentration in recipients on a general basis, or under what conditions OWTSs generally have such an impact. A compilation of groundwater studies may provide examples of how far the P may reach in x years, but the number of groundwater studies is insufficient to draw any general conclusions, given the complexity and variability of the systems. Future research should strive for replicated study designs, more elaborate reporting, and the establishment of a reporting standard.
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| 7. |
- Envall, Ida, et al.
(författare)
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What evidence exists related to soil retention of phosphorus from on-site wastewater treatment systems in boreal and temperate climate zones? : A systematic map protocol
- 2020
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Ingår i: Environmental Evidence. - : BMC. - 2047-2382. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Background Soil-based on-site wastewater treatment systems (OWSs) are suspected to contribute to eutrophication of surface waters, due to the discharge of phosphorus (P). However, along the flow path between the facilities and surface waters, different processes contribute to delay the transport of phosphorus through the ground. This may reduce the unwanted impact on receiving water bodies. However, the strength and significance of this so-called soil retention remains unclear. In Sweden, there are nearly one million OWSs. To protect surface waters, a high P removal rate (up to 90%) is often required by the local municipalities. However, since these requirements may have costly consequences to property owners, it is debated as to whether they are too strict. In this debate, it is often claimed that the retention of P occurring in natural environments may be underestimated by authorities. Accordingly, there is a need for a scrutiny of the available evidence related to soil retention of phosphorus from OWSs. This is the objective of the planned systematic map. Focus will be on boreal and temperate climate zones. Methods Searches will be made for peer-reviewed articles and grey literature using bibliographic databases, search engines, specialist websites and stakeholder contacts. The references will be screened for relevance according to a predefined set of eligibility criteria. At stage one, after testing and clarifying the eligibility criteria, the references will be single-screened based on title and abstract. At stage two, potentially relevant references will be screened in full-text independently by two reviewers. We will compile a detailed database of the relevant studies. Moreover, a narrative report will be produced, describing the research landscape in general terms. This will be carried out with a conceptual model, describing the processes involved in P retention in natural environments, as a foundation. It will be discussed where the respective studies/study types fit into the conceptual model, and also evaluated how each study/study type can be related to the overarching question of eutrophication. Moreover, we will describe identified knowledge gaps that warrant further primary research effort, as well as identified knowledge clusters that could be suitable for systematic reviews.
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| 8. |
- Gleisner, Magdalena, 1972-
(författare)
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Quantification of mineral weathering rates in sulfidic mine tailings under water-saturated conditions
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Tailings are a fine-grained waste product produced during the metal recovery process. Tailings consist mostly of different silicates but also sulfides (e.g. pyrite), since 100 % metal recovery is not possible. Freshly processed tailings are deposited in large impoundments. If the mine tailings in the impoundments are exposed to water and oxygen, the sulfides will oxidize and release acidity and metals such as Fe, Cu, Zn, and Pb. The sulfide mineral oxidation reactions are catalyzed by sulfur and iron oxidizing bacteria (principally Acidithiobacillus ferrooxidans) that oxidize ferrous iron to ferric iron, which then oxidizes pyrite. When the leachate produced by this process discharges from the impoundment, it is called acid mine drainage, which may lead to the pollution of adjacent streams and lakes.The intention with this thesis is to investigate and quantify mineral weathering processes and element release rates occurring in water-saturated and soil-covered sulfidic mine tailings. The study was performed in different batch and column experiments in room temperature and in the laboratory. The batch experiments were conducted for ca. three months and investigated: a) microbial and abiotic sulfide oxidation in freshly processed tailings under oxic conditions at pH 2-3 and pH 8, b) microbial oxidation of pure pyrite grains at pH 2-3 under different oxygen concentrations ranging from anoxic to oxic conditions. The column experiments, consisting of unoxidized tailings in water-saturated columns, were conducted for up to three years. In these experiments, an oxygen-saturated solution was continually pumped into the column inlet, and investigated: a) differences in oxidation rates between tailings of two different grain sizes, b) factors affecting element discharge rates, acid neutralization, and sulfide oxidation, c) the effect of ions released in a soil cover on release rates in the tailings.Sulfide oxidation processes within the batch experiments were limited by surface kinetics. The microbial oxidation of pure pyrite at atmospheric conditions produced the most rapid rate, while the microbial oxidation of pure pyrite at anoxic conditions was slower by 1.8 orders of magnitude. Microbial and abiotic oxidation of pyrite in freshly-processed tailings resulted in pyrite oxidation rates that were intermediate between these two extremes. The results from the microbial experiments with pure pyrite indicated a positive correlation between the concentration of dissolved oxygen, ferric iron and bacterial cells (at a total cell concentration > 106 cells/mL and a dissolved oxygen concentration ≥ 13.2 µM), which implies an interdependence of these factors. The results from these batch experiments support the indirect mechanism for microbial oxidation by the ferric oxidation pathway. Pyrite oxidation rates estimated from the batch experiments may be comparable with oxidation rates in the unsaturated zone and at the groundwater table in a tailings impoundment.Acid neutralization reactions in the column experiments resulted in the release of base cations to the column leachate. Calcite was the most important neutralizing mineral despite that it was only present in minor amounts in the tailings. It was confirmed that acidity forced the calcite dissolution. Element release rates in the column experiments were controlled by the availability of dissolved oxygen, which was a function of the water flow rate into the column. These column experiments also showed that the results are comparable with results from field studies, justifying the use of column experiments to study processes within tailings impoundments.
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| 9. |
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| 10. |
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| 11. |
- Ingri, Johan, et al.
(författare)
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Temporal variations in the fractionation of the rare earth elements in a boreal river; the role of colloidal particles.
- 2000
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Ingår i: Chemical Geology. - 0009-2541 .- 1872-6836. ; 166:1-2, s. 23-45
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Tidskriftsartikel (refereegranskat)abstract
- Rare earth element (REE) data from weekly sampling of the filtered (<0.45 μm) and suspended particulate phase during 18 months in the Kalix River, Northern Sweden, are presented together with data on colloidal particles and the solution fraction (<3 kDa). The filtered REE concentration show large seasonal and temporal variations in the river. Lanthanum varied between approximately 300 and 2100 pM. High REE concentration in the filter-passing fraction is related to increased water discharge and there is a strong correlation between the REE concentration, organic carbon, Al and Fe. Physical erosion of detrital particles plays a minor role for the yearly transport of particulate REE in this boreal river system. The suspended particulate fraction, which is dominated by non-detrital fractions, accounted for only 35% of the yearly total transport of La in the river. Approximately 10% of the REE were transported in detrital particles during winter. At spring-flood in May, about 30% of the LREE and up to 60% of the HREE where hosted in detrital particles. Ultrafiltration of river water during spring-flood shows that colloidal particles dominate the transport of filter-passing REE. Less than 5% of the filtered REE are found in the fraction smaller than 3 kDa. The colloidal fraction shows a flat to slightly LREE enriched pattern whereas the solution fraction (<3 kDa) show an HREE enriched pattern, compared with till in the catchment. Suspended particles show a LREE enriched pattern. Data indicate that the REE are associated with two phases in the colloidal (and particulate) fraction, an organic-rich phase (with associated Al-Fe) and an Fe-rich (Fe-oxyhydroxide) inorganic phase. The Ce-anomaly in the suspended particulate fraction in the river shows systematic variations, and can be used to interpret fractionation processes of the REE during weathering and transport. There was no anomaly at maximum spring-flood but during the ice-covered period the anomaly became more and more negative. The temporal and seasonal variations of the Ce-anomaly in the suspended particulate phase reflect transport of REE-C-Al-Fe-enriched colloids from the upper section of the till (and/or from mires) to the river at storm events.
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| 12. |
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| 13. |
- Kätterer, Thomas, et al.
(författare)
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Växtföljders påverkan på inlagring av organiskt kol i jordbruksmark : en systematisk översikt och samhällsekonomisk analys
- 2021
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Rapport (populärvet., debatt m.m.)abstract
- Ändrade växtföljder kan göra jordbruket mer klimatsmart Genom väl avvägda växtföljder inom jordbruket kan förlusten av organiskt kol i marken minskas. Det är bra både för klimatet och markens bördighet. Vi har undersökt vad vetenskapen säger om vilka grödor och växtföljder som minskar kolförlusterna mest. I den här rapporten redovisar vi en systematisk översikt (del 1) och en samhällsekonomisk analys (del 2). Den systematiska översikten reder ut hur olika växtföljder påverkar inlagring av kol i jordbruksmark. Syftet med en systematisk översikt är att identifiera all tillgänglig och relevant kunskap, kvalitetsgranska studierna och undersöka hur olika faktorer påverkar studieresultaten. I den här systematiska översikten har vi granskat över 7500 unika sökträffar, varav 125 vetenskapliga artiklar uppfyllde de på förhand uppställda urvalskriterierna och är inkluderade i översikten. Utifrån resultaten från den systematiska översikten har vi därefter genomfört en kostnadsnyttoanalys och beräknat den samhällsekonomiska lönsamheten av olika typer av växtföljder. Vi har också genomfört en styrmedelsanalys där vi diskuterar vad som kan vara ett lämpligt styrmedel för att få till stånd en ändring av växtföljder som leder till en ökad inlagring av kol på jordbruksmark.Del 1: Övergripande evidensgraderade slutsatser av den systematiska översiktenVi är säkra på att flerårsväxter har en positiv effekt på halten av organiskt kol i jorden inom varierade växtföljderVi är säkra på att baljväxter har en positiv effekt på halten av organiskt kol i jorden inom varierade växtföljderVi kan visa att det finns en positiv effekt på halten av organiskt kol i jorden av vissa varierade växtföljder och brukningsmetoder jämfört med en upprepad monokultur.Fler och mer detaljerade slutsatser presenteras i rapporten. De skillnader i halt av organiskt kol i jorden mellan olika typer av växtföljder vi rapporterar om här framkommer tydligast när många studier vägs samman, snarare än i enskilda studier, och det statistiska underlaget därmed blir större. I den systematiska översikten har vi även identifierat några typer av växtföljder som det kan behövas mer forskning om, samt brister i hur metoder och resultat ofta rapporteras och som författare av framtida vetenskapliga artiklar bör beakta.Del 2: Resultat av den samhällsekonomiska analysenModellberäkningar visar att det är samhällsekonomiskt lönsamt att inom jordbruket praktisera växtföljder som främjar inlagring av organiskt kol i jordbruksmark även om de på kort sikt ger en lägre avkastning för den enskilde jordbrukaren.Om styrmedel i form av ekonomiska ersättningar skulle bli aktuella för att öka intresset för växtföljder som främjar inlagring av organiskt kol i jordbruksmark kan omvänd auktionering vara ett fungerande alternativ. Införande och utformning av ett eventuellt styrmedel måste dock utredas djupare och förankras brett genom sedvanligt remissförfarande.
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| 14. |
- Land, Magnus, et al.
(författare)
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Ba/Sr, Ca/Sr and 87Sr/86Sr ratios in soil water and groundwater: implications for relative contributions to stream water discharge
- 2000
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Ingår i: Applied Geochemistry. - 0883-2927 .- 1872-9134. ; 15:3, s. 311-325
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Tidskriftsartikel (refereegranskat)abstract
- Barium/Sr and Ca/Sr ratios have been used to model the relative importance of different sources of stream water. Major and trace element concentrations together with 87Sr/86Sr ratios were measured in precipitation, soil water, groundwater and stream water in a small (9.4 km2) catchment in northern Sweden. The study catchment is drained by a first order stream and mainly covered with podzolized Quaternary till of granitic composition. It is underlain by a 1.8 Ga granite. A model with mixing equations used in an iterative mode was developed in order to separate the stream water into 3 subsurface components: soil water, shallow groundwater, and deep groundwater. Contributions from precipitation are thus not included in the model. This source may be significant for the stream water generation, but it does not interfere with the calculations of the relative contributions from the subsurface components. The results show that the deep groundwater constitutes between 5 and 20% of the subsurface water discharge into the stream water. The highest values of the deep groundwater fraction occur during base flow. Soil water dominates during snowmelt seasons, whereas during base flow it is the least important fraction. Soil water accounts for 10–100% of the subsurface water discharge into the stream water. Shallow groundwater accounts for up to 80% of the subsurface water discharge with the lowest values at peak discharge during snowmelt seasons and the highest values during base flow. The validity of the model was tested by comparing the measured 87Sr/86Sr ratios in the stream water with the 87Sr/86Sr ratios predicted by the model. There was a systematic difference between the measured and modelled 87Sr/86Sr ratios which suggests that the fraction of soil water is overestimated by the model, especially during spring flood. As a consequence of this overestimation of soil water the amount of shallow groundwater is probably underestimated during this period. However, it is concluded that the differences between measured and predicted values are relatively small, and that element ratios are potentially effective tracers for different subsurface water flowpaths in catchments.
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| 15. |
- Land, Magnus, et al.
(författare)
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Chemical weathering rates, erosion rates and mobility of major and trace elements in a boreal granitic till
- 2000
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Ingår i: Aquatic geochemistry. - 1380-6165 .- 1573-1421. ; 6:4, s. 435-460
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Tidskriftsartikel (refereegranskat)abstract
- Chemical weathering rates and erosionrates of granitic till in northern Sweden have beenestimated. The present-day chemical weathering rate iscompared with the long-term average weathering ratesince the last deglaciation approximately 8,700 yearsago. Also, the present-day release rates of major andtrace elements due to chemical weathering are comparedwith the mobility of these elements in a spodosolprofile as shown by soil water samples from the vadozezone. The estimation of the past weathering rate isbased on elemental depletion trends in a soil profile(typic haplocryod), whereas the present weatheringrate is based on elemental input/output budgets in asmall catchment ...
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| 16. |
- Land, Magnus, et al.
(författare)
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How do selected crop rotations affect soil organic carbon in boreo-temperate systems? A systematic review protocol
- 2017
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Ingår i: Environmental Evidence. - : Springer Science and Business Media LLC. - 2047-2382. ; 6:1
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Forskningsöversikt (refereegranskat)abstract
- Background: Soils are important global carbon pools that are under threat from intensive land use through a variety of agricultural practices. Sustainable management of agricultural soils may have the potential to mitigate climate change through increased carbon sequestration and increase their fertility. Among management practices to increase carbon sequestration, crop rotation designs have often been tested on yield effects in long-term agricultural experiments. However, in these studies, soil organic carbon (SOC) was monitored but not always the key objective. Thus, here we provide a method for a systematic review to test the effects of common crop rotations on SOC sequestration to provide evidence on the most sustainable management regimes that can promote SOC storage. Methods: This systematic review incorporates studies concerning selected crop rotations (rotations-vs-monocultures, legumes-vs-no legumes, and perennials-vs-annuals) collated in a recently completed systematic map on the effect of agricultural management on SOC, restricted to boreo-temperate systems (i.e., the warm temperate climate zone). Some 208 studies relevant for this systematic review were identified in the systematic map. An update of the original search (September 2013) will be undertaken to identify newly published academic and grey literature. Studies will be critically appraised for their internal and external validity, followed by full data extraction (meta-data describing study settings and quantitative study results). Where possible, studies will be included in meta-analyses examining the effects of the different rotational practices. Implications of the findings will be discussed in terms of policy, practice and research, and the nature of the evidence base.
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| 17. |
- Land, Magnus, et al.
(författare)
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How effective are created or restored freshwater wetlands for nitrogen and phosphorus removal? A systematic review
- 2016
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Ingår i: Environmental Evidence. - : Springer Science and Business Media LLC. - 2047-2382. ; 5:1
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Forskningsöversikt (refereegranskat)abstract
- Background: Eutrophication of aquatic environments is a major environmental problem in large parts of the world. In Europe, EU legislation (the Water Framework Directive and the Marine Strategy Framework Directive), international conventions (OSPAR, HELCOM) and national environmental objectives emphasize the need to reduce the input of nutrients to freshwater and marine environments. A widely used method to achieve this is to allow water to pass through a created or restored wetland. However, the large variation in measured nutrient removal rates in such wetlands calls for a systematic review. Methods: Searches for primary studies were performed in electronic databases and on the internet. One author performed the screening of all retrieved articles at the title and abstract level. To check that the screening was consistent and complied with the agreed inclusion/exclusion criteria, subsets of 100 articles were screened by the other authors. When screening at full-text level the articles were evenly distributed among the authors. Kappa tests were used to evaluate screening consistency. Relevant articles remaining after screening were critically appraised and assigned to three quality categories, from two of which data were extracted. Quantitative synthesis consists of meta-analyses and response surface analyses. Regressions were performed using generalized additive models that can handle nonlinear relationships and interaction effects. Results: Searches generated 5853 unique records. After screening on relevance and critical appraisal, 93 articles including 203 wetlands were used for data extraction. Most of the wetlands were situated in Europe and North America. The removal rate of both total nitrogen (TN) and total phosphorus (TP) is highly dependent on the loading rate. Significant relationships were also found for annual average air temperature (T) and wetland area (A). Median removal rates of TN and TP were 93 and 1.2 g m-2 year-1, respectively. Removal efficiency for TN was significantly correlated with hydrologic loading rate (HLR) and T, and the median was 37 %, with a 95 % confidence interval of 29-44 %. Removal efficiency for TP was significantly correlated with inlet TP concentration, HLR, T, and A. Median TP removal efficiency was 46 % with a 95 % confidence interval of 37-55 %. Although there are small differences in average values between the two quality categories, the variation is considerably smaller among high quality studies compared to studies with lower quality. This suggests that part of the large variation between studies may be explained by less rigorous study designs. Conclusions: On average, created and restored wetlands significantly reduce the transport of TN and TP in treated wastewater and urban and agricultural runoff, and may thus be effective in efforts to counteract eutrophication. However, restored wetlands on former farmland were significantly less efficient than other wetlands at TP removal. In addition, wetlands with precipitation-driven HLRs and/or hydrologic pulsing show significantly lower TP removal efficiencies compared to wetlands with controlled HLRs. Loading rate (inlet concentrations × hydraulic loading rates) needs to be carefully estimated as part of the wetland design. More research is needed on the effects of hydrologic pulsing on wetlands. There is also a lack of evidence for long-term (>20 years) performance of wetlands.
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| 18. |
- Land, Magnus, et al.
(författare)
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How effective are created or restored freshwater wetlands for nitrogen and phosphorus removal? A systematic review protocol
- 2013
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Ingår i: Environmental Evidence. - : BioMed Central. - 2047-2382. ; 2:16
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Tidskriftsartikel (refereegranskat)abstract
- Background: Eutrophication of aquatic environments is a major environmental problem in large parts of the world.In Europe, EU legislation (the Water Framework Directive and the Marine Strategy Framework Directive),international conventions (OSPAR, HELCOM) and national environmental objectives emphasize the need to reducethe input of plant nutrients to freshwater and marine environments. A widely used method to achieve this is to letwater pass through a constructed or restored wetland (CW). However, the large variation in measured nutrientremoval rates in such wetlands calls for a systematic review. The objective of this review is to quantify nitrogen andphosphorus removal rates in constructed or restored wetlands and relate them to wetland characteristics, loading characteristics, and climate factors. Wetlands are created to treat water from a number of different sources. Sources that will be considered in this review include agricultural runoff and urban storm water run-off, as well as aquaculture wastewater and outlets from domestic wastewater treatment plants, with particular attention to thesituation in Sweden. Although the performance of wetlands in temperate and boreal regions is most relevant tothe Swedish stakeholders a wider range of climatic conditions will be considered in order to make a thorough evaluation of climatic factors.Methods: Searches for primary studies will be performed in electronic databases as well as on the internet. Oneauthor will perform the screening of all retrieved articles at the title and abstract level. To check that the screeningis consistent and complies with the agreed inclusion/exclusion criteria, subsets of 100 articles will be screened by the other authors. When screening at full-text level the articles will be evenly distributed among the authors. Kappatests will be used to evaluate screening consistency. Data synthesis will be based on meta-regression. The nutrient removal rates will be taken as response variables and the effect modifiers will be used as explanatory variables. More specifically, the meta-regression will be performed using generalized additive models that can handle nonlinear relationships and major interaction effects. Furthermore, subgroup analyses will be undertaken to elucidate statistical relationships that are specific to particular types of wetlands.
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| 19. |
- Land, Magnus, et al.
(författare)
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Past and present weathering rates in northern Sweden
- 1999
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Ingår i: Applied Geochemistry. - 0883-2927 .- 1872-9134. ; 14:6, s. 761-774
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Tidskriftsartikel (refereegranskat)abstract
- Past and present chemical weathering rates in granitic till have been estimated. The Kalix River watershed in northern Sweden was used as a study area in which 17 evenly distributed soil profiles were investigated. The two estimations are based on elemental depletion trends in soil profiles and input/output budgets for the elements in the watershed, respectively. In the calculations of the past weathering rate it was assumed that zircon is resistant, and thus Zr was considered to be immobile during weathering. The long-term average chemical erosion rate since the area was deglaciated 8700 a ago, expressed as the sum of major element oxides (SiO2, Al2O3, CaO, Fe2O3, K2O, MgO, MnO, Na2O), was estimated to be 5.8 g·m−2·a−1. In terms of base cation (Ca2+, Mg2+, Na+, K+) depletion this corresponds to 0.36 keq·ha−2·a−1. All elements analysed have been depleted from the E-horizon, and the most affected elements are P with an average mass loss of 86% (as P2O5), La 81%, Co 78%, Cu 77% and Ni 76%. The present-day weathering rate was calculated as the difference between outputs and inputs in the Kalix River watershed. The input was considered as the contribution from precipitation, while the output was calculated as the sum of (1) the river-transported dissolved fraction, (2) the river-transported suspended non-detrital fraction (chemically precipitated Fe- and Mn-oxy-hydroxides and matter sorbed on these particles), and (3) the biotic nutrient net uptake. River-transported outputs were measured for an annual cycle starting in September 1991 and ending in August 1992. The present-day chemical erosion rate of the till was estimated to be 6.3 g·m−2·a−1 (sum of major element oxides), or a base cation flux of 1.42 keq·ha−2·a−1. Part of this present-day rate is related to carbonate weathering in the Caledonian mountain range which makes it difficult to compare the present weathering rate with the historical weathering rate. After correction for carbonate weathering the resulting present-day weathering rate of granitic till in terms of base cation flux was estimated to be 0.65–0.75 keq·ha−2·a−1. This result indicates that the present cation flux has increased by a factor of 1.8–2.1 compared to the long-term average. However, given the uncertainties introduced by the carbonates in the Caledonian mountain range it is not possible to prove any significant difference between the mean post-glacial and the present-day weathering rate with the methods used in this study.
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| 20. |
- Land, Magnus, et al.
(författare)
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Seasonal variations in the geochemistry of shallow groundwater hosted in granitic till
- 1997
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Ingår i: Chemical Geology. - 0009-2541 .- 1872-6836. ; 143:3-4, s. 205-216
-
Tidskriftsartikel (refereegranskat)abstract
- The groundwater chemistry in a small catchment in northern Sweden has been studied for a period of 15 months, including two snowmelt events. The groundwater was sampled from two wells in a slope facing a small stream. One well was placed at the top of the slope (28 m from the stream), and the other was placed closer to the stream (13 m from the stream). Both wells were completed to approximately the same elevation (1.5 m below the stream bed). In addition to groundwater compositions, the chemical composition of precipitation, soil water and stream water was investigated. The chemical composition of the groundwater in the well farther from the stream was fairly constant during the studied period. In the closer well the concentrations of Ca, Mg, Na, Sr, Si, and alkalinity decreased by approximately 10% during snowmelt in May. In contrast, the concentrations of Fe, Al, Ce and Cu increased. After the snowmelt, during June and July, the concentrations of Ca, Mg, Na, Sr, Si, and alkalinity in the closer well increased by a factor of 2–5 compared with the concentrations prior to the snowmelt. By August, the concentrations had decreased to the same levels as before the snowmelt and remained constant until next snowmelt. To explain these variations the Ca/Sr ratio was used as a natural chemical tracer for different water masses. It was found that the increased concentrations of Ca, Mg, Na, Sr, Si, and alkalinity during summer was caused by changes in the groundwater flow direction, which resulted in upwelling of deeper groundwater. At this time the area at the closer well acted as an unsaturated discharge area. The concentrations of Fe, Al, Ce and Cu decreased rapidly after the snowmelt and then remained constant except for two peaks in July and August. These variations were due to mixing with rapidly percolating soil water from the E-horizon and melt water or rain water, which is supported by increased content of dissolved oxygen.
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| 21. |
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| 22. |
- Land, Magnus, et al.
(författare)
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Solid speciation and fractionation of rare earth elements in a Spodosol profile from northern Sweden as revealed by sequential extraction
- 1999
-
Ingår i: Chemical Geology. - 0009-2541 .- 1872-6836. ; 160:1-2, s. 121-138
-
Tidskriftsartikel (refereegranskat)abstract
- A sequential extraction has been carried out on seven soil samples from a spodosol profile in till with granitic composition. The soil profile was sampled in northern Sweden. Five fractions were selected for extraction: (A) CH3COONa-extractable (exchangeable/adsorbed/carbonate); (B) Na4P2O7-extractable (labile organics); (C) 0.25 M NH2OH⋅HCl-extractable (amorphous Fe-oxyhydroxides/Mn-oxides); (D) 1 M NH2OH⋅HCl-extractable (crystalline Fe-oxides); and (E) KClO3/HCl-extractable (organics and sulphides). Extracted rare earth elements (REE) were determined with High Resolution ICP-MS. In addition to the soil, stream water suspended particulate matter was also analysed for REE. Total concentrations in the soil samples show that the REE have been fractionated during weathering. In the acidic (pH 4.28) E-horizon all REE are depleted relative to the unweathered till. The depletion decreases with increasing atomic number. Also in the B-horizon (pH 5.86) the REE are depleted, although to a lesser extent compared to the E-horizon. Secondary phases in the B-horizon fractionate the REE in different ways. Rare earth elements extracted in extractions A and C were enriched in the intermediate REE relative to heavy and light REE if normalized to local till. In extractions B and D, the heavy REE were enriched relative to the light REE, and in extraction E a large enrichment of light REE relative to heavy REE was found. Stream water suspended particulate matter is enriched in all REE relative to local till. The light REE are more enriched than the heavy REE. Normalized La/Lu ratios in the suspended matter ranged from 1.5 to 2.4, and were negatively correlated with stream water discharge as well as with content of detrital inorganic matter in the suspended load. The only extracted phase that potentially can explain the high normalized La/Lu ratio in the suspended matter is the phase extracted in extraction E, which has a ratio of 2.0–4.2. The normalized La/Lu ratio for the rest of the extractions ranged from 0.5 to 1.2. It is concluded that organic matter seems to be important for the particulate transport of REE in northern coniferous areas.
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| 23. |
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| 24. |
- Land, Magnus, et al.
(författare)
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Trace metal occurrence in a mineralised and a non-mineralised Spodosol in northern Sweden
- 2002
-
Ingår i: Journal of Geochemical Exploration. - 0375-6742 .- 1879-1689. ; 75:1-3, s. 71-91
-
Tidskriftsartikel (refereegranskat)abstract
- In order to determine the metal-bearing phases with special emphasis on Cu, a sequential extraction has been carried out on seven soil samples from a sulphide-bearing spodosol profile in Liikavaara Ostra, close to the Aitik Copper Mine in northern Sweden. A reference spodosol profile with very low abundances of sulphides located far from anthropogenic emissions was also studied. Five fractions were selected for the extraction: (I) CH (sub 3) COONa-extractable (exchangeable/adsorbed/carbonate); (II) Na (sub 4) P (sub 2) O (sub 7) -extractable (labile organics); (III) 0.25 M NH (sub 2) OH.HCl-extractable (amorphous Fe oxyhydroxides/Mn oxides); (IV) 1 M NH (sub 2) OH.HCl-extractable (crystalline Fe oxides); and (V) KClO (sub 3) /HCl-extractable (organics and sulphides). The distribution of trace elements (Co, Cr, Cu, Ni, Pb and Zn) in the profile in Liikavaara Ostra is different from that in the reference profile. Possible explanations for these differences are (i) the presence of sulphides in the soil, (ii) atmospheric deposition of dust derived from mining activities at the Aitik Copper Mine, and (iii) mineralogical heterogeneities inherited from the deposition of the till. There is no straightforward correlation between the amount of the extracted phases and the metal extractability in the soils. This fact indicates that other factors are important for the retention of trace metals as well. The data presented in this study suggest that Co, Cr and Ni, to a fairly large extent, are associated with the organic matter in the B-horizon in both profiles, while in the C-horizon in Liikavaara Ostra, sulphides are probably the more important carriers of these elements. For Co and Ni, Fe oxyhydroxides seem to be important. Most of the Cr occurred in the residual remaining after the leaching procedure. Copper and Zn seem to be associated with the organic matter to some extent in the B-horizon. The concentration of Cu in the C-horizon in Liikavaara Ostra is high (2310 ppm), but only a very small fraction is likely to be hosted by sulphides. It is concluded that the major part of Cu in the C-horizon and a prominent fraction in the B-horizon in Liikavaara Ostra are associated with some secondary phase that is extractable during extractions III and IV. Possible candidates for this phase are goethite and inclusions of native Cu in weathered biotite
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| 25. |
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| 26. |
- Land, Magnus, et al.
(författare)
-
Vittring och vattenkvalitet i norra Sverige
- 1996
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Geokemiska processer i ett litet, väl definierat dräneringsområde i norra Sverige har studerats. Detta har gjorts genom att provta och analysera markvatten, grundvatten och bäckvatten i en tidsserie som sträcker sig över en hel årscykel. Även nederbörden har provtagits och analyserats, men endast vid enstaka tillfällen. Markvattenproverna har tagits vid fyra olika djup. Djupen var 5 cm (E-horisonten), 15 cm (Bs1-horisonten), 40 cm (Bs2horisonten) och 100 cm (C-horisonten). Grundvattnet har provtagits från två grundvattenrör placerade i en sluttning ner mot en bäck. Det övre röret var placerat i ett inströmningsområde, och det nedre i ett omväxlande inströmnings~ och utströmningsområde. I bäckvattnet provtogs både löst och suspenderad fast fas. I vattenproverna har Ca, Fe, K, Mg, Nå, Si, Al, Sr, S, As, Ba, Cd, Ce, Co, Cr, Cu, Mn, Mo, Ni, Pb, Sr, U, Yb, och Zn analyserats med ICP-AES och ICP-MS. Förutom vattenprover har även moränprover provtagits. Proverna togs i en kontinuerlig profil från ytan ner till ett djup av 120 cm. Morän har också provtagits och analyserats på ytterligare två lokaler i norra Sverige. Moränproverna har analyserats med avseende på Si, Al, Ca, Fe, K, Mg, Mn, Nå, P, Ti, Ba, Be, Co, Cr, Cu, Ni, Sc, Sr, V, Zn och Zr (ICP-AES), samt Gå, Hf, Mo, Nb, Rb, Sn, Ta, Th, U, W, Y, La, Ce, Nd, Sm, Eu, Gd, Th, Dy, Ho, Er, Yb och Lu (ICP-MS).Resultaten visar att markvattnet har en mycket stor betydelse för tungmetallernas koncentrationer i bäckvattnet. Tungmetallhalterna är relativt höga i markvattnet från moränens E-horisont. En stor del av dessa tungmetaller härrör från nederbörden snarare än vittring. Längre ner i markprofilen sjunker tungmetallhalterna drastiskt. Det verkar som dessa i stor utsträckning fastläggs i marken, vilket resulterar i mycket låga halter i grundvattnet. I samband med snösmältning och kraftigt regn kan dock markvatten från E-horisonten tryckas ner till grundvattnet relativt snabbt och förhöja halterna av t ex Cu, men också av Fe och Al. Vid inledningen av snösmältningsperioder stiger tungmetallhalterna även i bäckvattnet. Detta sker till följd av att mycket av smältvattnet rinner till bäcken via E-horisonten eller humuslagret. Under den senare delen av snösmältningen sjunker tungmetallhalterna, men utspädningen är betydligt lägre än för huvudelementen. Efter snösmältningsperioden steg halterna av huvudelementen medan de förblev låga för tungmetallerna.Generellt har den nutida vittringshastigheten i det undersökta dräneringsområdet sjunkit jämfört med den genomsnittliga historiska vittringshastigheten. Den ser dock ut att ha ökat för Ca och Mg. Ökningen kan balanseras av våtdepositionen av sulfat. Detta kan tyda på att det sker en förändring av markens jonbytesförråd snarare än att den egentliga vittringen har ökat.
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| 27. |
- Land, Magnus
(författare)
-
Weathering of till in northern Sweden and its implications for the geochemistry of soil water, groundwater and stream water
- 1998
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Natural exogenic geochemical processes in northern Sweden have been studied. The thesis is focused on field weathering rates and variations in the chemical composition of water with time and space. Variations in weathering rates of silicate minerals are important for the global CO2 cycle, and thus also for climatic changes. Soil, soil water, groundwater, and stream water samples have been collected and analyzed. Complementary to the field studies, leaching experiments in the laboratory have also been performed. The results indicate that the release rates of SiO2, Al2O3, Fe2O3, K2O and Na2O due to weathering of till have decreased during the past 8700 years. The release rates of CaO and MgO appear to have increased. Chemical weathering of till is important for the chemical composition of soil water, groundwater and stream water in northern Sweden. Special emphasis is given to the mobility of heavy metals and rare earth elements during weathering.
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| 28. |
- Land, Magnus, et al.
(författare)
-
What is the effect of phasing out long-chain per- and polyfluoroalkyl substances on the concentrations of perfluoroalkyl acids and their precursors in the environment? A systematic review
- 2018
-
Ingår i: Environmental Evidence. - : Springer Science and Business Media LLC. - 2047-2382. ; 7:1
-
Forskningsöversikt (refereegranskat)abstract
- Background: There is a concern that continued emissions of man-made per-and polyfluoroalkyl substances (PFASs) may cause environmental and human health effects. Now widespread in human populations and in the environment, several PFASs are also present in remote regions of the world, but the environmental transport and fate of PFASs are not well understood. Phasing out the manufacture of some types of PFASs started in 2000 and further regulatory and voluntary actions have followed. The objective of this review is to understand the effects of these actions on global scale PFAS concentrations. Methods: Searches for primary research studies reporting on temporal variations of PFAS concentrations were performed in bibliographic databases, on the internet, through stakeholder contacts and in review bibliographies. No time, document type, language or geographical constraints were applied in the searches. Relevant subjects included human and environmental samples. Two authors screened all retrieved articles. Dual screening of 10% of the articles was performed at title/abstract and full-text levels by all authors. Kappa tests were used to test consistency. Relevant articles were critically appraised by four reviewers, with double checking of 20% of the articles by a second reviewer. Meta-analysis of included temporal trends was considered but judged to not be appropriate. The trends were therefore discussed in a narrative synthesis. Results: Available evidence suggests that human concentrations of perfluorooctane sulfonate (PFOS), perfluorodecane sulfonate (PFDS), and perfluorooctanoic acid (PFOA) generally are declining, while previously increasing concentrations of perfluorohexane sulfonate (PFHxS) have begun to level off. Rapid declines for PFOS-precursors (e.g. perfluorooctane sulfonamide, FOSA) have also been consistently observed in human studies. In contrast, limited data indicate that human concentrations of PFOS and PFOA are increasing in China where the production of these substances has increased. Human concentrations of longer-chained perfluoroalkyl carboxylic acids (PFCAs) with 9-14 carbon atoms are generally increasing or show insignificant trends with too low power to detect a trend. For abiotic and biological environmental samples there are no clear patterns of declining trends. Most substances show mixed results, and a majority of the trends are insignificant with low power to detect a trend. Conclusions: For electrochemically derived PFASs, including PFOS and PFOA, most human studies in North America and Europe show consistent statistically significant declines. This contrasts with findings in wildlife and in abiotic environmental samples, suggesting that declining PFOS, PFOS-precursor and PFOA concentrations in humans likely resulted from removal of certain PFASs from commercial products including paper and board used in food packaging. Increasing concentrations of long-chain PFCAs in most matrices, and in most regions, is likely due to increased use of alternative PFASs. Continued temporal trend monitoring in the environment with well-designed studies with high statistical power are necessary to evaluate the effectiveness of past and continuing regulatory mitigation measures. For humans, more temporal trend studies are needed in regions where manufacturing is most intense, as the one human study available in China is much different than in North America or Europe.
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| 29. |
- Land, Magnus, et al.
(författare)
-
What is the effect of phasing out long-chain per- and polyfluoroalkyl substances on the concentrations of perfluoroalkyl acids and their precursors in the environment? A systematic review protocol
- 2015
-
Ingår i: Environmental Evidence. - : Springer Science and Business Media LLC. - 2047-2382. ; 4:1
-
Forskningsöversikt (refereegranskat)abstract
- BackgroundThere is a growing concern in Sweden and elsewhere that continued emissions of per- and polyfluoroalkyl substances (PFASs) may cause environmental as well as human health effects. PFASs are a broad class of man-made substances that have been produced and used in both commercial products and industrial processes for more than 60 years. Although the production and use of some PFASs has been phased-out in some parts of the world, it is not known what effect these actions to date have had on PFAS concentrations in the environment. Owing to the wide diversity of PFASs, it is difficult to generalize their properties, environmental fate and production histories. However, the strength and stability of the C-F bond renders the perfluoroalkyl moieties resistant to heat and environmental degradation. Several PFASs are now occurring even in very remote areas in large parts of the world, but the environmental transport and fate of substances within this group is not well understood. A systematic review may be able to determine whether the concentrations of these substances in different environments are changing in any particular direction with time, and whether the phase-outs have had any effects on the concentration trends.MethodsSearches for primary research studies reporting on temporal variations of PFAS concentrations in the environment will be performed in the scientific literature as well as in other reports. Relevant samples include both abiotic and biological samples including humans. No particular time, document type, language or geographical constraints will be applied. Two authors will screen all retrieved articles. Double screening of about 10% of the articles will be performed by all authors at both title/abstract and full-text levels. Kappa tests will be used to test if the screening is consistent. Relevant articles will be critically appraised by four authors (double checking of 25% of the articles). Quality assessment will focus on selection bias, dating of samples, sample integrity and analytical procedures. Data synthesis will be based on statistical analysis of temporal concentration trends.
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| 30. |
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| 31. |
- Pei Breivold, Hongyu
(författare)
-
Software Architecture Evolution and Software Evolvability
- 2009
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Software is characterized by inevitable changes and increasing complexity, which in turn may lead to huge costs unless rigorously taking into account change accommodations. This is in particular true for long-lived systems. For such systems, there is a need to address evolvability explicitly during the entire lifecycle, carry out software evolution efficiently and reliably, and prolong the productive lifetime of the software systems. In this thesis, we study evolution of software architecture and investigate ways to support this evolution. The central theme of the thesis is how to analyze software evolvability, i.e. a system’s ability to easily accommodate changes. We focus on several particular aspects: (i) what software characteristics are necessary to constitute an evolvable software system; (ii) how to assess evolvability in a systematic manner; (iii) what impacts need to be considered given a certain change stimulus that results in potential requirements the software architecture needs to adapt to, e.g. ever-changing business requirements and advances of technology. To improve the capability in being able to on forehand understand and analyze systematically the impact of a change stimulus, we introduce a software evolvability model, in which subcharacteristics of software evolvability and corresponding measuring attributes are identified. In addition, a further study of one particular measuring attribute, i.e. modularity, is performed through a dependency analysis case study. We introduce a method for analyzing software evolvability at the architecture level. This is to ensure that the implications of the potential improvement strategies and evolution path of the software architecture are analyzed with respect to the evolvability subcharacteristics. This method is proposed and piloted in an industrial setting. The fact that change stimuli come from both technical and business perspectives spawns two aspects that we also look into in this research, i.e. to respectively investigate the impacts of technology-type and business-type of change stimuli.
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| 32. |
- Reynolds, Ben C., et al.
(författare)
-
An inter-laboratory comparison of Si isotope reference materials
- 2007
-
Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 22:5, s. 561-568
-
Tidskriftsartikel (refereegranskat)abstract
- Three Si isotope materials have been used for an inter-laboratory comparison exercise to ensure reproducibility between international laboratories investigating natural Si isotope variations using a variety of chemical preparation methods and mass spectrometric techniques. These proposed standard reference materials are (i) IRMM-018 (a SiO2 standard), (ii) Big-Batch (a fractionated SiO2 material prepared at the University of California Santa Barbara), and (iii) Diatomite (a natural diatomite sample originally deposited as marine biogenic opal). All analyses are compared with the international Si standard NBS28 (RM8546) and are in reasonable agreement (<+/- 0.22 parts per thousand. 1 sigma(SD) delta Si-30) given the different measurement techniques involved. These methods include both acid and alkaline dissolution/fusion, Si separation using cation exchange, selective co-precipitation, and gas-source versus plasma-ionization (high and low resolution) mass-spectrometric techniques. The average delta Si-30 for Diatomite, IRMM-018, and Big-Batch are + 1.26 parts per thousand, -1.65 parts per thousand and -10.48 parts per thousand, respectively, with corresponding delta Si-9 values of + 0.64 parts per thousand, -0.85 parts per thousand and -5.35 parts per thousand for the same standards, respectively. For the most fractionated standard (Big-Batch), results demonstrate a kinetic mass-dependent fractionation effect for atomic Si (i.e., delta Si-29 similar to 0.51 x delta Si-30). There is almost no statistical difference between the mean values obtained by each participating laboratory, with the notable exception of the IRMM-018 standard. This effect could be caused by heterogeneity or contamination of this standard. The results for the other two standards indicate that data sets produced using any of the methods employed in this study will have similar precision and differences are limited to 0.2 parts per thousand in mean delta Si-30 values for a given sample between laboratories, or differences of 0.13 parts per thousand. in mean delta Si-29 values.
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| 33. |
- Reynolds, Ben C., et al.
(författare)
-
An inter-laboratory comparison of Si isotope reference materials
- 2007
-
Ingår i: Journal of Analytical Atomic Spectrometry. - : Elsevier BV. - 0267-9477 .- 1364-5544. ; 22:5, s. 561-568
-
Tidskriftsartikel (refereegranskat)abstract
- Three Si isotope materials have been used for an inter-laboratory comparison exercise to ensure reproducibility between international laboratories investigating natural Si isotope variations using a variety of chemical preparation methods and mass spectrometric techniques. These proposed standard reference materials are (i) IRMM-018 (a SiO2 standard), (ii) Big-Batch (a fractionated SiO2 material prepared at the University of California Santa Barbara), and (iii) Diatomite (a natural diatomite sample originally deposited as marine biogenic opal). All analyses are compared with the international Si standard NBS28 (RM8546) and are in reasonable agreement (<+/- 0.22 parts per thousand. 1 sigma(SD) delta Si-30) given the different measurement techniques involved. These methods include both acid and alkaline dissolution/fusion, Si separation using cation exchange, selective co-precipitation, and gas-source versus plasma-ionization (high and low resolution) mass-spectrometric techniques. The average delta Si-30 for Diatomite, IRMM-018, and Big-Batch are + 1.26 parts per thousand, -1.65 parts per thousand and -10.48 parts per thousand, respectively, with corresponding delta Si-9 values of + 0.64 parts per thousand, -0.85 parts per thousand and -5.35 parts per thousand for the same standards, respectively. For the most fractionated standard (Big-Batch), results demonstrate a kinetic mass-dependent fractionation effect for atomic Si (i.e., delta Si-29 similar to 0.51 x delta Si-30). There is almost no statistical difference between the mean values obtained by each participating laboratory, with the notable exception of the IRMM-018 standard. This effect could be caused by heterogeneity or contamination of this standard. The results for the other two standards indicate that data sets produced using any of the methods employed in this study will have similar precision and differences are limited to 0.2 parts per thousand in mean delta Si-30 values for a given sample between laboratories, or differences of 0.13 parts per thousand. in mean delta Si-29 values.
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| 34. |
- Rodríguez, Nathalie Pérez
(författare)
-
Fractionation of Cu and Fe isotopes in metal-rich mine sites : biotic and abiotic processes
- 2012
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- After mineral exploitation the residual grinded and milled material, rich in sulphide minerals and heavy metals, is often left exposed to the atmospheric variables. This weathered mine waste material can lead to the formation of acid mine drainage (AMD) which has negative effects to the environment. The fractionation of stable isotope of metals such as Cu and Fe can be measured using innovative analytical techniques developed recently and could offer a detailed hindsight of the geochemical processes occurring in mine contaminated sites. Tailings profiles from Northern Sweden with high content of Cu and Fe sulphides and in different stages of weathering and/or remediation, along with plant and soil samples from a phytoremediation test site in Ronneburg, Germany were analysed using MC-ICP-MS to measure the isotope ratios of 65Cu/63Cu and 56Fe/54Fe. The analytical method used requires anion exchange chromatography to extract Cu and Fe from a complex matrix prior to the proper isotope ratio measurement. The samples from the tailings profile were useful to interpret the geochemical processes that can lead to a fractionation of Cu and Fe in the field, since redox-driven reactions such as rock oxidation and mineral precipitation are present in such environment. This study shows that precipitation of covellite in a redox-boundary zone in a mine tailings can cause a clear fractionation of Cu (Δ65Curock-covellite= -5.66±0.05‰) and a depletion of the lighter Cu isotope in the oxidised areas of the tailings due to dissolution of the remaining Cu-sulphides. Precipitation of Fe(oxy)hydroxides as a result of the oxidation process of sulphide-bearing rocks can also fractionate Fe, being the precipitated mineral slightly enriched in 56Fe.The influence of soil bacteria and plant uptake in the fractionation of Cu and Fe was investigated in pot and field experiments at the Ronneburg site, where organic amendments were used. The results showed that the plant material was enriched in the lighter Fe isotope compared to the substrate used in the pot and field experiments, in spite of the application of a bacterial consortium. Cu isotope fractionation is more susceptible to the changes in the amendments used, being those bacterial consortium, mychorriza or compost than Fe isotope fractionation. There are differences in the fractionation values in pot and field trials, regardless of the type of organic amendment applied. As an overall view, leaves are enriched in the heavier Cu isotope compared to the soils, regardless of the amendment usedThe application of the results obtained in this work would help not only to offer a view in the cycle of Fe and Cu in the surface environment, and the understanding of the (bio)geochemical processes occurring in sulphide soil surfaces. But also in the way that current remediation techniques of metal contaminated sites could be evaluated, having in mind that simplified systems show a different Cu and Fe fractionation compared to natural systems where more variables are needed to take into account.
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| 35. |
- Seifollahi-Aghmiuni, Samaneh, et al.
(författare)
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Change Drivers and Impacts in Arctic Wetland LandscapesLiterature Review and Gap Analysis
- 2019
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Ingår i: Water. - : MDPI AG. - 2073-4441. ; 11:4
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Forskningsöversikt (refereegranskat)abstract
- Wetlands are essential parts of Arctic landscapes, playing important roles for the sustainable development of the region, and linking to climate change and adaptation, ecosystem services, and the livelihood of local people. The effects of human and natural change drivers on key landscape characteristics of Arctic wetlands may be critical for ecosystem resilience, with some functional aspects still poorly understood. This paper reviews the scientific literature on change drivers for Arctic wetland landscapes, seeking to identify the main studied interactions among different drivers and landscape characteristics and their changes, as well as emerging research gaps in this context. In a total of 2232 studies of various aspects of Arctic wetland landscapes found in the literature, natural drivers and climate change have been the most studied change drivers so far, particularly regarding their impacts on carbon cycling, plant communities and biodiversity. In contrast, management plans, land use changes, and nutrient-pollutant loading, have not been investigated as much as human drivers of Arctic wetland change. This lack of study highlights essential gaps in wetland related research, and between such research and management of Arctic wetlands.
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| 36. |
- Öhlander, Björn, et al.
(författare)
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Change of Sm-Nd isotope composition during weathering of till
- 2000
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Ingår i: Geochimica et Cosmochimica Acta. - 0016-7037 .- 1872-9533. ; 64:5, s. 813-820
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Tidskriftsartikel (refereegranskat)abstract
- Weathering of till in northern Sweden results in the formation of well-developed spodosols. The till is dominated by 1.9–1.8 Ga granitic material. The REE are among the elements most strongly depleted during weathering, and the loss of REE from the E-horizon decreases as the atomic number increases. To study if weathering leads to a change of the Nd isotope composition, we have analysed the Nd isotopic composition of the various horizons including living plants and humus of two profiles of weathered till (typic haplocryods) in northern Sweden. As much as between 65.6 and 75.3% of the Sm and Nd in the <0.2 mm fraction has been lost from the E-horizon, and between 32.5 and 54.7% from the B-horizon. Nd has been lost to a slightly greater extent than Sm. The two C-horizon samples have εNd(0) values of −22.1 and −23.2. Corresponding E-horizon values are −18.1 and −20.2. The B-horizon values are intermediate between the values of the E and C horizons. It is concluded that the weathering leads to a change in the Sm/Nd ratio resulting in a change of the Sm-Nd isotope composition. The plant and humus samples deviate even more from the unweathered till. For one station the results could be interpreted as if the Sm and Nd taken up by the plants had similar isotope characteristics as the amounts of these elements released by weathering in the E-horizon. For the other station it is probable that the Nd isotope composition of the organic samples is dominated by Nd released by till weathering which, however, is mixed with another Nd-source, possibly an airborne component. The explanation to the change of isotope compostion in the till is that a larger proportion of the Nd released by weathering is released from minerals with a lower Sm/Nd ratio than the bulk soil, compared with the amount released from minerals with a higher Sm/Nd ratio. Although the various REE-carrying minerals had the same initial Nd isotopic composition, 1.8–1.9 Ga of decay of 147Sm to 143Nd has resulted in a higher present 143Nd/144Nd ratio in the minerals with a higher Sm/Nd ratio.
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| 37. |
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| 38. |
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| 39. |
- Öhlander, Björn, et al.
(författare)
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Mobility and transport of Nd isotopes in the Vadose zone during weathering of granitic till in a boreal forest
- 2014
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Ingår i: Aquatic geochemistry. - : Springer Science and Business Media LLC. - 1380-6165 .- 1573-1421. ; 20:1, s. 1-17
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Tidskriftsartikel (refereegranskat)abstract
- There is a broad correlation between the εNd values for rivers (including both the water and the particulate material it carries) and the age of the source terrain. This paper presents Nd isotope distribution data for soil, soil water, groundwater, and stream water samples gathered in a small catchment in northern Sweden. The results show that the release of Nd and Sm from boreal forests into streams and, eventually, into the oceans is more complicated than previously realized. The weathering of till causes changes in both the Nd isotopic composition and Sm/Nd ratios. Both the Sm/Nd ratio and εNd were higher in strongly weathered soils horizons than in less weathered till, since minerals with high Sm/Nd ratios were, on average, more resistant to weathering than those with low Sm/Nd ratios. In contrast to the situation for the main minerals and the major elements, the weathering of rare earth elements (REE) was not restricted to the E-horizon: the measured REE concentrations continued to increase with depth in the C-horizon. In addition, REE released by weathering in the upper parts of the soil profile were partly secondarily retained at deeper levels. Therefore, the dissolved Nd released by weathering in the upper soil horizons was trapped and did not enter the groundwater directly. Rather, the Nd in the groundwater largely originated from weathering within the groundwater zone. However, this was not the only source of Nd in the stream water. The Nd isotope composition and Sm/Nd ratio were determined by the mixing between of Nd and Sm in the groundwater and REE-carrying organic material washed out of the soil profile. The groundwater close to the stream reaches the upper soil horizons during high discharge events such as snowmelts, and organic matter carrying Nd and Sm is washed out of the soils and thus released into the stream. Therefore, the Nd exported from catchment is derived from both the weathering within the groundwater zone, and the organic matter washed out from the soil. If longer timescales with more advanced weathering stages in the groundwater zone are considered, it cannot be ruled out that there will be a shift towards more radiogenic values in the exported Nd. Recorded shifts in the Nd isotopic composition in the ocean may thus not only reflect changed source regions, but also the weathering history of the same source region
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| 40. |
- Öhlander, Björn, et al.
(författare)
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Mobility of rare earth elements during weathering of till in northern Sweden
- 1996
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Ingår i: Applied Geochemistry. - : Elsevier BV. - 0883-2927 .- 1872-9134. ; 11:1-2, s. 93-99
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Tidskriftsartikel (refereegranskat)abstract
- Continuous, volume-controlled sampling from the surface down to a depth of 130 cm was conducted at two stations on weathered till (typic haplocryods). All the samples were analysed for major and trace elements including the rare earth elements (REE). Eight thousand seven hundred years of weathering since the glacial ice left the area, has resulted in a strong depletion of REE in the E-horizon. This loss decreases as atomic number increases, so that 80-85% of the La and 54-60% of the Yb have been lost. Europium has been lost to a greater degree than have the neighbouring elements. Possible explanations for the release of REE are: weathering of common silicates such as hornblende and epidote (and plagioclase in the case of Eu); weathering of apatite; weathering of rare but REE-rich minerals such as allanite and monazite; and release of REE adsorbed on clay minerals. Further studies on various size fractions and minerals are needed to quantify the importance of the various possible mechanisms of REE release. The release of REE continues within and below the Bs1-horizon, but the results from one station show that light REE can be enriched in the Bs1-horizon. This secondary enrichment could be caused by adsorption on secondary oxy-hydroxides, on clay minerals or on organic material. However, the net result of the weathering is that all REE have been released to the groundwater.
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| 41. |
- Öhlander, Björn, et al.
(författare)
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Redistribution of trace metals in a mineralized spodosol due to weathering, Liikavaara, northern Sweden
- 2003
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Ingår i: Applied Geochemistry. - 0883-2927 .- 1872-9134. ; 18:6, s. 883-899
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Tidskriftsartikel (refereegranskat)abstract
- The till east of the Liikavaara Östra ore deposit in northern Sweden is in some parts rich in Cu and other sulphide-associated metals. Groundwater flowing in this till has higher concentrations of Cu than groundwater in a reference area where the till has low concentrations of Cu and other metals. To understand the processes that release metals from the mineralized till at Liikavaara into the groundwater, the authors performed a detailed study of the <2 mm fraction of a till profile where the highest metal concentrations in the Liikavaara area occur. The geochemistry and mineralogy of the till were determined, and the soil water was sampled by tension lysimeters. The importance of local diffusion of Cu-bearing airborne dust from the adjacent Aitik mine tailings impoundment was quantified and solid speciation of metals in airborne material was performed by sequential extraction. The results from Liikavaara were compared to results from the reference area. Glacial ice picked up sulphide-rich material from the Liikavaara Östra Cu ore during its flow. This material was deposited in the till east of the ore body when the ice melted. The sulphides have been dissolved in the <2 mm fraction during 8.7 ka of weathering since the glacial ice retreated. After dissolution of the sulphides, Cu was redistributed and secondarily retained in association with Fe-oxyhydroxides and altered biotite. Other sulphide-associated elements such as Co, Ni and Zn show the same pattern in the till profile as Cu, though the concentrations are much lower. Uptake of Cu2+ in the biotite through ion exchange with K+ may be an important mechanism for Cu-enrichment in biotite at Liikavaara. The airborne dust is not the source of Cu in the till. Although the soil water at Liikavaara has higher concentrations of Cu and other metals than the soil water at the reference area, the Cu-concentration is too low for infiltrating soil water to explain the high Cu-concentrations observed in groundwater. The high metal concentrations in the till, of Cu in particular, cause the increased concentrations in the local groundwater. A fluctuating groundwater table washes out Cu and other metals from the till. It is possible that increased Cu concentration in the local groundwater is caused by dissolved organic complexes, or by colloids (<0.45 μm) rich in organic matter and/or Fe-oxyhydroxides.
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