| 41. |
- Winterdahl, Mattias, et al.
(författare)
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Riparian Zone Influence on Stream Water Dissolved Organic Carbon Concentrations at the Swedish Integrated Monitoring Sites
- 2011
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 40:8, s. 920-930
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Tidskriftsartikel (refereegranskat)abstract
- Short-term variability in stream water dissolved organic carbon (DOC) concentrations is controlled by hydrology, climate and atmospheric deposition. Using the Riparian flow-concentration Integration Model (RIM), we evaluated factors controlling stream water DOC in the Swedish Integrated Monitoring (IM) catchments by separating out hydrological effects on stream DOC dynamics. Model residuals were correlated with climate and deposition-related drivers. DOC was most strongly correlated to water flow in the northern catchment (Gammtratten). The southern Aneboda and Kindla catchments had pronounced seasonal DOC signals, which correlated weakly to flow. DOC concentrations at GAyenrdsjon increased, potentially in response to declining acid deposition. Soil temperature correlated strongly with model residuals at all sites. Incorporating soil temperature in RIM improved model performance substantially (20-62% lower median absolute error). According to the simulations, the RIM conceptualization of riparian processes explains between 36% (Kindla) and 61% (Aneboda) of the DOC dynamics at the IM sites.
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| 42. |
- Ritter, Camila, et al.
(författare)
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High-throughput metabarcoding reveals the effect of physicochemical soil properties on soil and litter biodiversity and community turnover across Amazonia.
- 2018
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Ingår i: PeerJ. - : PeerJ. - 2167-8359. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge on the globally outstanding Amazonian biodiversity and its environmental determinants stems almost exclusively from aboveground organisms, notably plants. In contrast, the environmental factors and habitat preferences that drive diversity patterns for micro-organisms in the ground remain elusive, despite the fact that micro-organisms constitute the overwhelming majority of life forms in any given location, in terms of both diversity and abundance. Here we address how the diversity and community turnover of operational taxonomic units (OTU) of organisms in soil and litter respond to soil physicochemical properties; whether OTU diversities and community composition in soil and litter are correlated with each other; and whether they respond in a similar way to soil properties.We used recently inferred OTUs from high-throughput metabarcoding of the 16S (prokaryotes) and 18S (eukaryotes) genes to estimate OTU diversity (OTU richness and effective number of OTUs) and community composition for prokaryotes and eukaryotes in soil and litter across four localities in Brazilian Amazonia. All analyses were run separately for prokaryote and eukaryote OTUs, and for each group using both presence-absence and abundance data. Combining these with novel data on soil chemical and physical properties, we identify abiotic correlates of soil and litter organism diversity and community structure using regression, ordination, and variance partitioning analysis.Soil organic carbon content was the strongest factor explaining OTU diversity (negative correlation) and pH was the strongest factor explaining community turnover for prokaryotes and eukaryotes in both soil and litter. We found significant effects also for other soil variables, including both chemical and physical properties. The correlation between OTU diversity in litter and in soil was non-significant for eukaryotes and weak for prokaryotes. The community compositions of both prokaryotes and eukaryotes were more separated among habitat types (terra-firme, várzea, igapó and campina) than between substrates (soil and litter).In spite of the limited sampling (four localities, 39 plots), our results provide a broad-scale view of the physical and chemical correlations of soil and litter biodiversity in a longitudinal transect across the world's largest rainforest. Our methods help to understand links between soil properties, OTU diversity patterns, and community composition and turnover. The lack of strong correlation between OTU diversity in litter and in soil suggests independence of diversity drives of these substrates and highlights the importance of including both measures in biodiversity assessments. Massive sequencing of soil and litter samples holds the potential to complement traditional biological inventories in advancing our understanding of the factors affecting tropical diversity.
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| 43. |
- Hawkes, Jeffrey A., et al.
(författare)
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Regional diversity of complex dissolved organic matter across forested hemiboreal headwater streams
- 2018
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Dissolved organic matter (DOM) from soils enters the aquatic environment via headwater streams. Thereafter, it is gradually transformed, removed by sedimentation, and mineralised. Due to the proximity to the terrestrial source and short water residence time, the extent of transformation is minimal in headwaters. DOM has variable composition across inland waters, but the amount of variability in the terrestrial end member is unknown. This gap in knowledge is crucial considering the potential impact large variability would have on modelling DOM degradation. Here, we used a novel liquid chromatography –mass spectrometry method to characterise DOM in 74 randomly selected, forested headwater streams in an 87,000 km2 region of southeast Sweden. We found a large degree of sample similarity across this region, with Bray-Curtis dissimilarity values averaging 8.4 ± 3.0% (mean ± SD). The identified variability could be reduced to two principle coordinates, correlating to varying groundwater flow-paths and regional mean temperature. Our results indicate that despite reproducible effects of groundwater geochemistry and climate, the composition of DOM is remarkably similar across catchments already as it leaves the terrestrial environment, rather than becoming homogeneous as different headwaters and sub-catchments mix.
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| 44. |
- Konn, Cécile, 1981-, et al.
(författare)
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Detection of trace organic compounds by Stir Bar Sorptive Extraction: application to the evolution of the organic composition of hydrothermal fluids from the Rainbow site (36°N, Mid-Atlantic Ridge) over 3 years
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The question of the abiogenic oil has been discussed and hydrothermal reactions have been suggested to abiotically generate hydrocarbons. Besides, ultramafic-hosted hydrothermal systems have been regarded as favourable environment for the emergence of life. Therefore, it is of great importance to investigate the presence of organic compounds in hydrothermal fluids. However, because of the sampling difficulties, the complexity of the matrix, the numerous interferences and the assumed trace level concentrations; it was considered a real challenge. Here we show that Stir Bar Sorptive Extraction (SBSE) coupled to Thermal Desorption – Gas Chromatography – Mass Spectrometry (TD-GC-MS) can be successfully applied to analyses of volatile and semi-volatile organic compounds in hydrothermal fluids. The method exhibited excellent reproducibility and conditioned samples appeared to be really stable for up to 3 years. This innovative and versatile technique was used to study the fluids from the ultramafic-hosted hydrothermal field Rainbow located at 36°14’N on the Mid-Atlantic Ridge (MAR). Despite relative stability for mineral composition and gas content is observed, analyses of fluids samples from 2005, 2007 and 2008 revealed more distinct organic compositions. In addition, results suggest the similarity of the organic content of the fluids regardless of the sampling location within the field, which may indicates the presence of a single reaction zone and that no further chemical reactions occur while fluids are transported to the seafloor.
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| 45. |
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| 46. |
- Quintana, Isabel, et al.
(författare)
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Växtplankton
- 2015
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Ingår i: Vänern: Årsskrift 2015. ; 91, s. 36-39
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 47. |
- Eveborn, David, 1978-, et al.
(författare)
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Phosphorus in soil treatment systems : accumulation and mobility
- 2014
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Ingår i: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 64, s. 42-52
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Tidskriftsartikel (refereegranskat)abstract
- In several western countries, septic tanks with subsequent soil treatment systems (STS) are a common treatment technique for domestic wastewater in rural areas. However the suitability of STS (especially relatively close to surface waters) can be questioned since the discharge of phosphorus (P) from such effluents is not well known. In this study, six STS in Sweden (11 to 28 years old) were investigated by means of batch and column experiments on samples taken from the unsaturated subsoil beneath the distribution pipes. At all sites the wastewater had clearly influenced the soil. This was observed through decreased pH, increased amounts of oxalate extractable metals and altered P sorption properties. The amount of accumulated P in the STS (defined as the amount of total P in the STS samples minus the amount of total P in unused soil samples) were found to be between 0.32 and 0.87 kg m-3, which in most cases was just a small fraction of the estimated P load (< 30%). Column studies revealed that remarkably high P concentrations (up to 6 mg L-1) were leached from the material when deionized water was applied. However, the response to deionized water varied between the sites. The affinity for P in the soils was well correlated to the amount of oxalate-extractable aluminium (as evidenced by a strong relationship between oxalate-extractable Al and oxalate-extractable P) and generally soils with high content of oxalate extractable Al was also less vulnerable to P leakage.
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| 48. |
- Zhang, Yi Ge, et al.
(författare)
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Refining the alkenone-pCO2 method II : Towards resolving the physiological parameter ‘b’
- 2020
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Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier BV. - 0016-7037 .- 1872-9533. ; 281, s. 118-134
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Tidskriftsartikel (refereegranskat)abstract
- Haptophyte algal biomarkers called alkenones are widely used to reconstruct atmospheric CO2 in Earth’s Cenozoic history. This method is based on the notion that the algal carbon isotope fractionation during photosynthesis, as represented by ep37:2, is a function of seawater CO2 concentration and algal physiology. Constraining the algal physiological parameter, known as the ‘b’ term, is the key for successful applications of the alkenone-CO2 method. Using sensitivity analyses, we show that the growth rate (µ), cell size (r), and membrane permeability (P) are the most important variables to determine b. For all life on Earth, body size is a key factor that regulates metabolic rates. Exploiting the interdependence between phytoplankton cell size and growth rate, and specifically, the r – µ relationship for coccolithophores, we show that the length of fossil coccoliths (Lcoccolith) produced by ancient alkenone-synthesizers can be used to estimate r and therefore µ. Combining our new Lcoccolith data and published ep37:2 from the South China Sea Site MD01-2392, existing results from ODP Site 925, and ice core CO2, we determined the cell membrane permeability (P = 5.09 10-5 m s-1) for the Pleistocene community employing a bootstrap resampling technique. These new methods of constraining r, µ and P, combined with proxy-derived temperature (T), led us to rebuild b as a variable for each sample individually, which is subsequently used for alkenone-CO2 calculations. Application of this approach established pCO2 of the last 3 glacial-interglacial cycles, which turns out to be comparable with the ice core data in both the amplitude of changes and absolute values. It also reconciles the published Eocene – Oligocene alkenone-CO2 data which showed large geographical differences, with the new estimates much more consistent among different sites, and in line with other proxy-based results and ice sheet model predictions.
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| 49. |
- Moldan, Filip, et al.
(författare)
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Bedömningsgrunder försurning - tester av MAGIC-biblioteket
- 2022
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Rapport (refereegranskat)abstract
- IVL Svenska Miljöinstitutet har tillsammans med Sveriges lantbruksuniversitet (SLU) på uppdrag av Havs-och vattenmyndigheten undersökt ett antal frågeställningar angående bedömningsverktyget MAGIC-biblioteket baserade på synpunkter och data från kalkningsansvariga handläggare på länsstyrelserna.MAGIC-biblioteket är ett försurningsbedömningsverktyg som gör att sjöar och vattendrag kan bedömas utifrån ett liknande vatten. På det sättet har tiotusentals sjöar och vattendrag bedömts. I samband med bedömningarna har det identifierats ett antal fall där beräknade referensvärden bedömts vara orealistiska utifrån annan kunskap som användarna av MAGIC-biblioteket besitter. Ett utskick gjordes till kalkningsansvariga handläggare på länsstyrelserna där det efterfrågades underlag på sådana objekt där försurningsbedömning med MAGIC-biblioteket anses vara felaktig. Så mycket relevant bakgrundsinformation som möjligt efterfrågades för att möjliga förklaringar till de olika bedömningarna skulle kunna undersökas. Svar kom in från åtta länsstyrelser. Utifrån det insamlade materialet jämfördes MAGIC (Model of Acidification of Groundwater in Catchments)-modellerade objekt och MAGIC-bibliotekets resultat med historiska fiskdata, med uppmätt vattenkemi inklusive trender över tid och en jämförelse med uppmätt och modellerat atmosfäriskt nedfall gjordes.I studien jämfördes förekomst av mört från slutet av 1800-talet i Värmland med modellerad vattenkemi. Mört har förekommit i merparten av sjöarna, inklusive sjöar med lågt modellerat pH. Det är dock en tydligt minskande andel sjöar med förekomst av mört ju lägre modellerat pH vattnen har. Detta skiljer sig från till exempel den betydligt mindre försurningskänsliga abborren, där inget samband mellan förekomst och historiskt modellerat pH kunde urskiljas. Sjöar med lågt pH och där mört förekom i slutet av 1800-talet har i genomsnitt högre halt av löst organiskt kol än sjöar med högre pH.En jämförelse mellan uppmätta tidsserier från sjöar samt modellerade värden för samma sjö i MAGIC-biblioteket visar att magnituden av den modellerade trenden i många fall större än den observerade trenden. Bilden är inte helt entydig och skillnaderna är större för sulfat än för ANC (syraneutraliserande förmåga), men att modellen överskattar trenden förekommer betydligt oftare än tvärt om. Detta beror till största delen på att det finns en tendens för modellen att överskatta sulfathalten i sjöarna vid den tidpunkt då vattenförekomsterna började provtas. Orsaken till detta kan variera, men korrekt modellering av tidstrender i avrinningen förutsätter att tidsutvecklingen av nedfallet av svavel, kväve och baskatjoner som användes i modelleringen följt verkligheten även på platser och under tidsperioder där det inte finns data att grunda modellberäkningar på.
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