| 1. |
- Temnerud, Johan, et al.
(författare)
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Spatial patterns of some trace elements in four Swedish stream networks
- 2013
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 10, s. 1407-1423
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Tidskriftsartikel (refereegranskat)abstract
- Four river basins in southern Sweden, with catchment sizes from 0.3 to 127 km(2) (median 1.9), were sampled in October 2007. The 243 samples were analysed for 26 trace elements (Ag, As, Au, Ba, Be, Bi, Cd, Co, Cr, Cu, Ga, Ge, In, La, Li, Mo, Ni, Pb, Sb, Se, Sn, Tl, Ti, U, V and Zn) to identify spatial patterns within drainage networks. The range and median of each element were defined for different stream orders, and relationships to catchment characteristics, including deposition history, were explored. The sampling design made it possible to compare the differences along 40 stream reaches, above and below 53 stream junctions with 107 tributaries and between the 77 inlets and outlets of 36 lakes. The largest concentration differences (at reaches, junctions and lakes) were observed for lakes, with outlets usually having lower concentration compared to the inlets for As, Ba, Be, Bi, Cd, Co, Cr, Ga, Ge, Ni, Pb, Sn, Ti, Tl, U, V and Zn. Significantly lower concentrations were observed for Cd and Co when comparing headwaters with downstream sites in each catchment. Common factor analysis (FA) revealed that As, Bi, Cr, Ga, Ge, Tl and V co-vary positively with Al, Fe and total organic carbon (TOC) and negatively with La, Li and pH. The strong removal of a large number of trace elements when passing through lakes is evident though in the FA, where lake surface coverage plots opposite to many of those elements. Forest volume does not respond in a similar systematic fashion and, surprisingly, the amount of wetland does not relate strongly to either Fe or TOC at any of the rivers. A better understanding of the quantitative removal of organic carbon and iron will aid in understanding trace element fluxes from landscapes rich in organic matter and iron.
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| 2. |
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| 3. |
- Angeler, David, et al.
(författare)
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Managing ecosystems without prior knowledge: pathological outcomes of lake liming
- 2017
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Ingår i: Ecology and Society. - 1708-3087. ; 22
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Tidskriftsartikel (refereegranskat)abstract
- Management actions often need to be taken in the absence of ecological information to mitigate the impact of pressing environmental problems. Managers counteracted the detrimental effects of cultural acidification on aquatic ecosystems during the industrial era using liming to salvage biodiversity and ecosystem services. However, historical contingencies, i.e., whether lakes were naturally acidic or degraded because of acidification, were largely unknown and therefore not accounted for in management. It is uncertain whether liming outcomes had a potentially detrimental effect on naturally acidic lakes. Evidence from paleolimnological reconstructions allowed us to analyze community structure in limed acidified and naturally acidic lakes, and acidified and circumneutral references. We analyzed community structure of phytoplankton, zooplankton, macroinvertebrates (littoral, sublittoral, profundal), and fish between 2000 and 2004. Naturally acidic limed lakes formed communities that were not representative of the other lake types. The occurrence of fish species relevant for ecosystem service provisioning (fisheries potential) in naturally acidic limed lakes were confounded by biogeographical factors. In addition, sustained changes in water quality were conducive to harmful algal blooms. This highlights a pathological outcome of liming lakes when their naturally acidic conditions are not accounted for. Because liming is an important social-ecological system, sustained ecological change of lakes might incur undesired costs for societies in the long term.
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| 4. |
- Badian, Reza A., et al.
(författare)
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Wide-field mosaics of the corneal subbasal nerve plexus in Parkinsons disease using in vivo confocal microscopy
- 2021
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Ingår i: Scientific Data. - : Nature Portfolio. - 2052-4463. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- In vivo confocal microscopy (IVCM) is a non-invasive imaging technique facilitating real-time acquisition of images from the live cornea and its layers with high resolution (1-2 mu m) and high magnification (600 to 800-fold). IVCM is extensively used to examine the cornea at a cellular level, including the subbasal nerve plexus (SBNP). IVCM of the cornea has thus gained intense interest for probing ophthalmic and systemic diseases affecting peripheral nerves. One of the main drawbacks, however, is the small field of view of IVCM, preventing an overview of SBNP architecture and necessitating subjective image sampling of small areas of the SBNP for analysis. Here, we provide a high-quality dataset of the corneal SBNP reconstructed by automated mosaicking, with an average mosaic image size corresponding to 48 individual IVCM fields of view. The mosaic dataset represents a group of 42 individuals with Parkinsons disease (PD) with and without concurrent restless leg syndrome. Additionally, mosaics from a control group (n = 13) without PD are also provided, along with clinical data for all included participants.
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| 5. |
- Bergknut, Magnus, et al.
(författare)
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Modelling the fate of hydrophobic organic contaminants in a boreal forest catchment : a cross disciplinary approach to assessing diffuse pollution to surface waters
- 2010
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Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491 .- 1873-6424. ; 158:9, s. 2964-2969
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Tidskriftsartikel (refereegranskat)abstract
- The fate of hydrophobic organic compounds (HOCs) in soils and waters in a northern boreal catchment was explored through the development of a chemical fate model in a well-characterised catchment system dominated by two land types: forest and mire. Input was based solely on atmospheric deposition, dominated by accumulation in the winter snowpack. Release from soils was governed by the HOC concentration in soil, the soil organic carbon fraction and soil-water DOC content. The modelled export of selected HOCs in surface waters ranged between 11 and 250ng day(-1) during the snow covered period, compared to 200 and 9600ng/d during snow-melt; highlighting the importance of the snow pack as a source of these chemicals. The predicted levels of HOCs in surface water were in reasonable agreement to a limited set of measured values, although the model tended to over predict concentrations of HOCs for the forested sub-catchment, by over an order of magnitude in the case of hexachlorobenzene and PCB 180. This possibly reflects both the heterogeneity of the forest soils and the complicated and changing hydrology experienced between the different seasons.
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| 6. |
- Bolou-Bi, Bolou Emile, et al.
(författare)
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Use of stable Mg isotope ratios in identifying the base cation sources of stream water in the boreal Krycklan catchment (Sweden)
- 2022
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Ingår i: Chemical Geology. - : Elsevier. - 0009-2541 .- 1872-6836. ; 588
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Tidskriftsartikel (refereegranskat)abstract
- The knowledge of the sources of base cations in stream water is a prerequisite to assess potential effects of changing environmental conditions such as changing rainfall, weathering or groundwater flows on cation export with stream water. This study use stable Mg isotopes to identify potential sources in the well-studied catchment of Krycklan located on gneissic bedrock covered by quaternary sediments in Sweden. Samples were collected from open filed rain, throughfall, stream, soil, rock and litterfall. The delta Mg-26 values of these samples was determined and the contributions of different sources to Mg fluxes in the stream were determined from the variation of the Mg isotope and Sr / Mg ratios. The results show an overall variation of 1.10 parts per thousand between all samples. In addition, Magnesium isotope ratios varied little in the streamwater and in soil solution, except during snowmelt periods during which a large portion of the annual runoff occurs. Magnesium in the streamwater is explained as a mixture of three pools (open field rain, soil solution and groundwater) with the latter two influenced by catchment processes. Outside the snow-melt period, Mg in streamwater mainly derived from the groundwater, assumed to be mineral weathering signature in this catchment, with a contribution ranging from 12 to 63% to Mg fluxes. Open field rain dominates Mg fluxes in streamwater during spring flood (0 to 78%) and may contribute significantly during larger summer and autumn rainfall events. Soil solution input to streamwater range from 16 to 59% of Mg fluxes in streamwater. Our results demonstrate that delta Mg-26 values together with Mg concentrations and Sr/Mg ratios can be used to constrain the Mg sources of stream water and quantify weathering release rates.
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| 7. |
- Campeau, Audrey, et al.
(författare)
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Sources of riverine mercury across the Mackenzie River Basin; inferences from a combined Hg C isotopes and optical properties approach
- 2022
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 806, s. 150808-150808
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Tidskriftsartikel (refereegranskat)abstract
- The Arctic terrestrial environment harbors a complex mosaic of mercury (Hg) and carbon (C) reservoirs, some of which are rapidly destabilizing in response to climate warming. The sources of riverine Hg across the Mackenzie River basin (MRB) are uncertain, which leads to a poor understanding of potential future release. Measurements of dissolved and particulate mercury (DHg, PHg) and carbon (DOC, POC) concentration were performed, along with analyses of Hg stable isotope ratios (incl. ∆199Hg, d202Hg), radiocarbon content (∆14C) and optical properties of DOC of river water. Isotopic ratios of Hg revealed a closer association to terrestrial Hg reservoirs for the particulate fraction, while the dissolved fraction was more closely associated with atmospheric deposition sources of shorter turnover time. There was a positive correlation between the ∆14C-OC and riverine Hg concentration for both particulate and dissolved fractions, indicating that waters transporting older-OC (14C-depleted) also contained higher levels of Hg. In the dissolved fraction, older DOC was also associated with higher molecular weight, aromaticity and humic content, which are likely associated with higher Hg-binding potential. Riverine PHg concentration increased with turbidity and SO4 concentration. There were large contrasts in Hg concentration and OC age and quality among the mountain and lowland sectors of the MRB, which likely reflect the spatial distribution of various terrestrial Hg and OC reservoirs, including weathering of sulfate minerals, erosion and extraction of coal deposits, thawing permafrost, forest fires, peatlands, and forests. Results revealed major differences in the sources of particulate and dissolved riverine Hg, but nonetheless a common positive association with older riverine OC. These findings reveal that a complex mixture of Hg sources, supplied across the MRB, will contribute to future trends in Hg export to the Arctic Ocean under rapid environmental changes.
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| 8. |
- Cascone, C., et al.
(författare)
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AbspectroscoPY, a Python toolbox for absorbance-based sensor data in water quality monitoring
- 2022
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Ingår i: Environmental Science. - : Royal Society of Chemistry (RSC). - 2053-1400 .- 2053-1419. ; 8:4, s. 836-848
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Tidskriftsartikel (refereegranskat)abstract
- The long-term trend of increasing natural organic matter (NOM) in boreal and north European surface waters represents an economic and environmental challenge for drinking water treatment plants (DWTPs). High-frequency measurements from absorbance-based online spectrophotometers are often used in modern DWTPs to measure the chromophoric fraction of dissolved organic matter (CDOM) over time. These data contain valuable information that can be used to optimise NOM removal at various stages of treatment and/or diagnose the causes of underperformance at the DWTP. However, automated monitoring systems generate large datasets that need careful preprocessing, followed by variable selection and signal processing before interpretation. In this work we introduce AbspectroscoPY (“Absorbance spectroscopic analysis in Python”), a Python toolbox for processing time-series datasets collected by in situ spectrophotometers. The toolbox addresses some of the main challenges in data preprocessing by handling duplicates, systematic time shifts, baseline corrections and outliers. It contains automated functions to compute a range of spectral metrics for the time-series data, including absorbance ratios, exponential fits, slope ratios and spectral slope curves. To demonstrate its utility, AbspectroscoPY was applied to 15-month datasets from three online spectrophotometers in a drinking water treatment plant. Despite only small variations in surface water quality over the time period, variability in the spectrophotometric profiles of treated water could be identified, quantified and related to lake turnover or operational changes in the DWTP. This toolbox represents a step toward automated early warning systems for detecting and responding to potential threats to treatment performance caused by rapid changes in incoming water quality.
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| 9. |
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| 10. |
- Drakare, Stina, et al.
(författare)
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Fokus på Mälaren 2020 : sammanfattande resultat från miljöövervakning och forskningsprojekt knutna till samarbetet mellan SLU och Mälarens vattenvårdsförbund
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Samarbetet mellan Mälarens vattenvårdsförbund (MVVF) och Sveriges lantbruksu-niversitet (SLU) fortsätter. Under 2020 påverkade pandemin möjligheterna att ses fysiskt under MVVF:s årsstämma och höstens Mälarseminarium. Vi lyckades hålla Mälarseminariet och några Mälarinarier som digitala möten vilka var välbesökta. Även miljöövervakningen kunde genomföras som planerat. Kännetecknande för 2020 var den milda vintern som inledde året med mycket ne-derbörd i form av regn. Det gjorde västra och nordöstra delarna av sjön grumliga under vår och försommar. Det är svårt att säga om det tydligt påverkade övriga mätvärden. Totalfosforhalterna var något högre än året innan vilket skulle kunna vara en effekt, men syrgashalterna i bottenvattnet var i stället bättre än året innan. Det verkar inte som att sedimentationsprocesser av det grumliga vattnet generellt påverkade syrgashalterna negativt. Statusbedömningen visar att stationer med måttlig status dominerar. I år hade fyra av 33 provtagna stationer god ekologisk status. Det är något bättre än året innan då bara två stationer hade god status. I år visas som vanligt resultat från Crosslink-projektet som visat att trädbevuxna kantzoner är positivt för livet i bäcken. Två artiklar och en film är nyheter för året från detta projekt som just avslutats. Flera doktorander har disputerat under våren och deras resultat från studier av organiska miljöföroreningar i Mälaren samt hur man kan rena bort dem i vattenverken har presenterats. Nytt för i år är att vi visar resultat från forskning om det viktiga växtnäringsämnet fosfor som man vill be-hålla på land där den gör nytta för gröda istället för att göda algblomningar i sjön. Flera projekt studerar de processer som förklarar hur fosforläckage till vatten sker samt hur man kan stoppa upp dem på vägen genom åtgärder i form av våtmarker och även genom att odla musslor i sjön. Årets studentprojekt är delvis kopplade till forskningen och har bland annat handlat om reningstekniker för dricksvatten för att få bort organiska ämnen av flera typer, analys av miljöföroreningar i sjöns tillrinnande vatten, och modellering av hur or-ganiskt material rör sig i sjön.
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