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1.
  • Agstam-Norlin, O., et al. (författare)
  • A 25-year retrospective analysis of factors influencing success of aluminum treatment for lake restoration
  • 2021
  • Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 200
  • Tidskriftsartikel (refereegranskat)abstract
    • For more than 50 years, aluminum (Al)-salts have been used with varying degrees of success to inactivate excess mobile phosphorus (P) in lake sediments and restore lake water quality. Here, we analyzed the factors influencing effectiveness and longevity of Al-treatments performed in six Swedish lakes over the past 25 years. Trends in post-treatment measurements of total phosphorus (TP), Chlorophyll a (Chl_a), Secchi disk depth (SD) and internal P loading rates (Li) were analyzed and compared to pre-treatment conditions. All measured water quality parameters improved significantly during at least the first 4 years post-treatment and determination of direct effects of Al-treatment on sediment P release (Li) was possible for three lakes. Improvements in TP (-29 to -80%), Chl_a (-50 to -78%), SD (7 to 121%) and Li (-68 to -94%) were observed. Treatment longevity, determined via decreases in surface water TP after treatment, varied from 7 to >47 years. Lake type, Al dose, and relative watershed area were related to longevity. In addition, greater binding efficiency between Al and P was positively related to treatment longevity, which has not previously been shown. Our findings also demonstrate that adequate, long-term monitoring programs, including proper determination of external loads, are crucial to document the effect of Al-treatment on sediment P release and lake water quality.
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3.
  • Ahlgren, Joakim, et al. (författare)
  • Degradation of organic phosphorus compounds in anoxic Baltic Sea sediments : A P-31 nuclear magnetic resonance study
  • 2006
  • Ingår i: Limnology and Oceanography. - Uppsala Univ, Dept Ecol & Evolut, Evolutionary Biol Ctr, S-75236 Uppsala, Sweden. Uppsala Univ, Dept Chem, S-75124 Uppsala, Sweden. Univ So Denmark, Inst Biol, DK-5230 Odense, Denmark.. - 0024-3590 .- 1939-5590. ; 51:5, s. 2341-2348
  • Tidskriftsartikel (refereegranskat)abstract
    • The composition and abundance of phosphorus extracted by NaOH-ethylenediaminetetraacetic acid from anoxic Northwest Baltic Sea sediment was characterized and quantified using solution P-31 nuclear magnetic resonance. Extracts from sediment depths down to 55 cm, representing 85 yr of deposition, contained 18.5 g m(-2) orthophosphate. Orthophosphate monoesters, teichoic acid P, microbial P lipids, DNA P, and pyrophosphate corresponded to 6.7, 0.3, 1.1, 3.0, and 0.03 g P m(-2), respectively. The degradability of these compound groups was estimated by their decline in concentration with sediment depth. Pyrophosphate had the shortest half-life (3 yr), followed by microbial P lipids with a half-life of 5 yr, DNA P (8 yr), and orthophosphate monoesters (16 yr). No decline in concentration with sediment depth was observed for orthophosphate or teichoic acid P.
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5.
  • Ahlgren, Joakim, 1972- (författare)
  • Organic Phosphorus Compounds in Aquatic Sediments : Analysis, Abundance and Effects
  • 2006
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Phosphorus (P) is often the limiting nutrient in lacustrine and brackish eco-systems, and enhanced input of P into an aquatic system might therefore negatively impact the environment. Because modern waste water manage-ment have reduced external P input to surface waters, internal P loading from the sediment has become one of the main P sources to aquatic ecosys-tems, in which relatively unknown organic P compounds seem to be more active in P recycling than previously thought. This thesis focus is on improving analysis methods for organic P com-pounds in lacustrine and brackish sediments, as well as determining which of these compounds might be degraded, mobilized and subsequently recycled to the water column and on what temporal scale this occur. In both lacustrine and brackish environments, the most labile P compound was pyrophosphate, followed by different phosphate diesters. Phosphate monoesters were the least labile organic P compounds and degraded the slowest with sediment depth. In regulated lakes, it was shown that pyrophosphate and polyphos-phate compound groups were most related to lake trophic status, thus indi-cating their involvement in P cycling. This thesis also indicates faster P turn-over in sediment from the brackish environment compared to sediment from the lacustrine environment. A comparison of organic P extraction procedures showed that pre-extraction with EDTA, and NaOH as main extractant, was most efficient for total P extraction. Using buffered sodium dithionite (BD) as a pre-extractant and NaOH as main extractant was most efficient for extracting the presuma-bly most labile organic P compound groups, pyrophosphate and polyphos-phate. Furthermore, it was determined that organic P compounds associated with humic substances were more recalcitrant than other P compounds, that the BD step used in traditional P fractionation might extract phosphate monoesters, and that NMR is a statistically valid method for quantification of organic P compounds in sediment extracts.
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6.
  • Ahlgren, Joakim, et al. (författare)
  • Release of Organic P Forms from Lake Sediments
  • 2011
  • Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 45:2, s. 565-572
  • Tidskriftsartikel (refereegranskat)abstract
    • The effects of different physical and chemical conditions on the decomposition and release of organic and inorganic P compound groups from the sediment of Lake Erken were investigated in a series of laboratory experiments. Conditions investigated were temperature, oxygen level, and the effects of additions of carbon substrate (glucose) and poison (formalin). The effects on the P compound groups were determined by measurements with 31P NMR before and after the experiments, as well as analysis of P in effluent water throughout the experiment. Phosphate analysis of the effluent water showed that oxygen level was the most influential in terms of release rates, with the sediments under anoxic conditions generally releasing more phosphate than the other treatments. 31P NMR showed that the various treatments did influence the P compound group composition of the sediment. In particular, the addition of glucose led to a decrease in orthophosphate and polyphosphate while the addition of formalin led to a decrease in phosphorus lipids, DNAphosphate and polyphosphate. Oxic conditions resulted in an increase in polyphosphates, and anoxic conditions in a decrease in these. Temperature did not seem to affect the composition significantly.
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7.
  • Ahlgren, Joakim, et al. (författare)
  • Sediment Depth Attenuation of Biogenic Phosphorus Compounds Measured by 31P NMR
  • 2005
  • Ingår i: Environmental Science and Technology. - Univ Uppsala, Dept Analyt Chem, SE-75124 Uppsala, Sweden. Univ Uppsala, Dept Ecol & Evolut, Uppsala, Sweden. Univ Uppsala, Dept Organ Chem, SE-75124 Uppsala, Sweden. : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 39:3, s. 867-872
  • Tidskriftsartikel (refereegranskat)abstract
    • Being a major cause of eutrophication and subsequent loss of water quality, the turnover of phosphorus (P) in lake sediments is in need of deeper understanding. A major part of the flux of P to eutrophic lake sediments is organically bound or of biogenic origin. This P is incorporated in a poorly described mixture of autochthonous and allochthonous sediment and forms the primary storage of P available for recycling to the water column, thus regulating lake trophic status. To identify and quantify biogenic sediment P and assess its lability, we analyzed sediment cores from Lake Erken, Sweden, using traditional P fractionation, and in parallel, NaOH extracts were analyzed using 31P NMR. The surface sediments contain orthophosphates (ortho-P) and pyrophosphates (pyro-P), as well as phosphate mono- and diesters. The first group of compounds to disappear with increased sediment depth is pyrophosphate, followed by a steady decline of the different ester compounds. Estimated half-life times of these compound groups are about 10 yr for pyrophosphate and 2 decades for mono- and diesters. Probably, these compounds will be mineralized to ortho-P and is thus potentially available for recycling to the water column, supporting further growth of phytoplankton. In conclusion, 31P NMR is a useful tool to asses the bioavailability of certain P compound groups, and the combination with traditional fractionation techniques makes quantification possible.
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8.
  • Ahlgren, Joakim, et al. (författare)
  • Sediment Phosphorus Extractants for Phosphorus-31 Nuclear Magnetic Resonance Analysis : A Quantitative Evaluation
  • 2007
  • Ingår i: Journal of Environmental Quality. - Uppsala Univ, Dept Phys & Analyt Chem, S-75124 Uppsala, Sweden. Univ So Denmark, Inst Biol, DK-5230 Odense M, Denmark. Uppsala Univ, Dept Biochem & Organ Chem, S-75124 Uppsala, Sweden. Uppsala Univ, Dept Ecol & Evolut, S-75123 Uppsala, Sweden. : Wiley. - 0047-2425 .- 1537-2537. ; 36:3, s. 892-898
  • Tidskriftsartikel (refereegranskat)abstract
    • The influence of pre-extractant, extractant, and post-extractant on total extracted amounts of P and organic P compound groups measured with 31P nuclear magnetic resonance (31P-NMR) in lacustrine sediment was examined. The main extractants investigated were sodium hydroxide (NaOH) and sodium hydroxide ethylenediaminetetraacetic acid (NaOH-EDTA) with bicarbonate buffered dithionite (BD) or EDTA as pre-extractants. Post extractions were conducted using either NaOH or NaOH-EDTA, depending on the main extractant. Results showed that the most efficient combination of extractants for total P yield was NaOH with EDTA as pre-extractant, yielding almost 50% more than the second best procedure. The P compound groups varying the most between the different extraction procedures were polyphosphates and pyrophosphates. NaOH with BD as pre-extractant was the most efficient combination for these compound groups.
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9.
  • Andrén, Cecilia M., et al. (författare)
  • Toxicity of inorganic aluminium at spring snowmelt—In-stream bioassays withbrown trout (Salmo trutta L.)
  • 2012
  • Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 437, s. 422-432
  • Tidskriftsartikel (refereegranskat)abstract
    • Although the acid load has decreased throughout Scandinavia, acidic soils still mobilise aluminium (Al) thatis harmful to brown trout. We hypothesise that there are thresholds for Al toxicity and that the toxicity can betraced from the water content to gill accumulation and the consequential physiological effects. During snowmelt,yearlings were exposed to a gradient of pH and inorganic monomeric Al (Ali) in humic streams to studythe toxic effects and mortality. Gill Al and physiological blood analyses [haemoglobin (Hb), plasma chloride(P-Cl) and glucose (Glu)] were measured. As the water quality deteriorated, Al accumulated on the gills; Hband Glu increased; P-Cl decreased, and mortality occurred. Moribund fish had significantly increased gill Aland Hb, suggesting that respiratory disturbances contributed to mortality. Decreased P-Cl and plasmaavailability indicated an ion regulatory disturbance and possibly circulatory collapse. Ali should be lessthan 20 μg/L, and pH higher than 5.0, to sustain healthy brown trout populations. These thresholds can beused to fine-tune lime dose, as both Ali and pH levels have to be balanced to prevent harm in the recoveringaquatic biota. Although Al is tightly linked to pH, local variation in Al availability in soil and bedrock affectsthe Al release and subsequent toxic Ali episodes in some catchment areas.
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10.
  • Andrén, Cecilia M., 1964- (författare)
  • Toxicity of Inorganic Aluminium in Humic Streams
  • 2012
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Aluminium (Al) has been recognised as a main toxic factor alongside pH in acidified water ecosystems. The toxic effect of Al has been attributed to inorganic Al (Ali), though there are few in situ studies in ambient humic waters which are the focus of this thesis.The aim was to estimate Ali toxicity and thus also Ali concentrations in Swedish humic streams. Subsequently it is necessary to analyse Ali correctly, which was studied by modelling and method intercalibrations. The hypothesis was that the effect of Ali could be followed via physiological effects and Al accumulation, as well as by mortality. Toxicity was studied by in stream exposures of brown trout (Salmo trutta L.) and two salmonid prey organisms (Gammarus pulex and Baetis rhodani) during spring flood.The modelling of the Ali fraction was performed using monitoring data covering all of Sweden with satisfactory results. The essential variables for Ali modelling were determined; Al, DOC, pH and F, while Fe, Ca and Mg had less effect. The automated analytical procedure for Ali (with cation exchange followed by complexation with pyrocatechol violet) was modified and validated and showed to be the preferred method for laboratory analyses.To avoid detrimental effects for brown trout Ali should be <20 µg/L and pH >5.0; mortality was high when the Ali was above 50 µg/L. The invertebrates were more sensitive, as mortalities occurred at pH <6.0 and Ali >15 µg/L for G. pulex, and at pH <5.7 and Ali >20 µg/L for B. rhodani. It is prudent to use a wide view and let the most sensitive species set the tolerance limits; a pH above 5.7-6.0 and Ali below 15-20 µg/L allows the stream ecosystems to thrive.Today, as waters are recovering from acidification, the aim of mitigating liming is to carefully adjust dosage to avoid suboptimal water quality. The thresholds found in this thesis can be used to efficiently but carefully decrease liming, as both Ali and pH levels have to be balanced to sustain the recovering aquatic biota.
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11.
  • Andrén, Cecilia M, et al. (författare)
  • Which aluminium fractionation method will give true inorganic monomeric Al results in fresh waters (not including colloidal Al)?
  • 2009
  • Ingår i: Journal of Environmental Monitoring. - : Royal Society of Chemistry (RSC). - 1464-0325 .- 1464-0333. ; 11:9, s. 1639-1646
  • Tidskriftsartikel (refereegranskat)abstract
    • Aluminium solubility and toxicity increase with acidification. There is no standardized analytical method for the determination of inorganic monomeric Al (Alim), which is the form that causes toxicity to fish. Separation by cation exchange is commonly combined with other analytical methods, such as complexation with pyrochatechol violet (PCV) or 8-hydroxyquinoline (HQ) and total quantification using graphite furnace or inductively-coupled plasma emission. Data from 14 laboratories were obtained for a dilution series of Alim samples; the results of the Alim analysis were statistically evaluated. The Alim levels were altered through pH, which was controlled by the addition of calcium hydroxide. Confounding parameters such as total organic carbon (TOC) or fluoride (F) were controlled. The total determination and HQ methods yielded significantly higher Alim concentrations than the PCV method. Pretreatment by passage through a 0.45 µm filter and pH-adjustment of the ion exchange column had no apparent effect on the Alim yield. However, ultra filtration (<10 kDa) caused a significant reduction in the Alim concentration using the HQ method. The ultra filtrated Alim fraction was similar to the PCV results in the interlaboratory comparison. Retention of colloidal bound Al in the cation exchange column may result in overestimation of Alim when the total and HQ methods are used. Estimated Alim concentrations derived from two equilibrium models were similar to PCV-derived Alim concentrations, as well as the HQ method using ultra filtrated water. The fact that the PCV method does not detect colloidal Al, neither before nor after ion exchange, makes this a preferred technique for Alim analysis. Because of the variability in the reported Alim concentrations that can arise when different analytical procedures are used, the adoption of a single, reliable technique will facilitate inter-study comparisons and provide consistency in the detection of trends in environmental monitoring programs.
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12.
  • Bergström, Lena, et al. (författare)
  • Fish community responses to restoration of a eutrophic coastal bay
  • 2024
  • Ingår i: Ambio. - 0044-7447 .- 1654-7209. ; 53, s. 109-125
  • Tidskriftsartikel (refereegranskat)abstract
    • Interest in coastal restoration measures is increasing, but information about subsequent ecosystem recovery processes is limited. In Bjornofjarden on the Baltic Sea coast, Stockholm archipelago, a pioneering case study to reduce coastal eutrophication led to improvements and initially halved phosphorus levels. Here, we evaluate the effects of the restoration on the local fish assemblage over one decade after the measures. The study gives a unique possibility to evaluate responses of coastal fish to nutrient variables and abatement in a controlled natural setting. Cyprinid abundance decreased and perch partially increased with decreasing turbidity levels, while mean trophic level increased over time in the restored area. Responses were overall weak, likely attributed to an attenuation of the eutrophication abatement effect over time. The results suggest that nutrient reduction gives slow responses in fish compared to alternative measures such as fishing closures.
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  • Carey, Cayelan C., et al. (författare)
  • Lake trophic status can be determined by the depth distribution of sediment phosphorus
  • 2011
  • Ingår i: Limnology and Oceanography. - : Wiley. - 0024-3590 .- 1939-5590. ; 56:6, s. 2051-2063
  • Forskningsöversikt (refereegranskat)abstract
    • In this meta-analysis, we examine how sediment phosphorus (P) burial pattern may be related to trophic state. We present sediment P profiles from 94 lakes that demonstrate fundamental differences in P burial between oligotrophic and eutrophic systems. In sediments of eutrophic (>= 30 mu g water column total P (TP) L-1) lakes, P concentrations are elevated in the surficial sediments in comparison with deeper layers, representing a large P pool that can be recycled. This pattern directly contrasts with sediment P profiles in oligotrophic lakes (< 10 mu g water column TP L-1), which exhibit increasing concentrations of permanently buried P with depth. Sediment processes regulating P burial may be important regulators of internal P recycling and consequently lake trophic status. Thus, mesotrophic lakes (10 to 30 mu g water column TP L-1), which exhibit consistent P concentrations with depth, are more vulnerable to external P inputs than oligotrophic lakes because they are at their maximal sediment P burial flux. Our data suggest that thresholds in sediment P pattern may correlate with thresholds in sediment P burial processes and consequently may indicate whether deposited P will be released to the water column.
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16.
  • De Brabandere, Heidi, 1980- (författare)
  • Organic Phosphorus Compounds in Aquatic Sediments : Towards Molecular Identification with Mass Spectrometry
  • 2008
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Phosphorus (P) regulates trophic status in most aquatic systems. However, only bioavailable P contributes to primary production. In most lakes and shallow seas, mineralisation of sediment P into its bioavailable form and its release to the water column is important for maintaining primary production. Sediment organic P forms a substantial proportion of this P to be mineralised and can originate from different sources on land (farmland, forests, etc.) or from primary production in the lake. These organic P forms can thus be expected to have differing composition, degradability and recyclable P content. Knowledge of the chemical structure of sediment organic P compounds is scarce, mainly due to lack of appropriate analytical techniques. The commonly used 31P-nuclear magnetic resonance (31P-NMR) technique, only identifies P binding groups, so a mass spectrometric (MS) analysis method was developed that allows individual sediment organic P compounds to be identified. EDTA as pre-extractant resulted in the highest P yield in subsequent NaOH extraction. Extracted organic P compound groups were identified using 31P-NMR. For identification of specific P compounds with MS, a sample preparation method prior to electrospray tandem mass spectrometry (ESI-MS/MS) analysis was developed. Liquid chromatography (LC) with porous graphitic carbon prior to ESI-MS/MS enhanced sensitivity and selectivity, enabling several of the ions detected to be identified as nucleotides. 31P-NMR analysis showed P monoesters to be the most stabile P compounds throughout a lake sediment profile. The developed LC-ESI-MS/MS analysis method revealed that some monoester-P (nucleotides) were labile, while other P compounds increased in concentration with Baltic Sea sediment depth and were therefore considered stabile. Differences in patterns of P compounds detected were also shown depending on catchment characteristics in relation to Baltic Sea sediment age. For cost-effective management of eutrophication, knowledge of the sources of degradable organic P forms, contributing to internal loading, is needed. This thesis showed the developed LC-ESI-MS/MS analysis method to be a powerful analytical tool for this purpose.
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17.
  • De Brabandere, Heidi, et al. (författare)
  • Screening for Organic Phosphorus Compounds in Aquatic Sediments by Liquid Chromatography Coupled to ICP-AES and ESI-MS/MS
  • 2008
  • Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 80:17, s. 6689-6697
  • Tidskriftsartikel (refereegranskat)abstract
    • The structures of organic phosphorous (P) compounds in aquatic sediments are to a large extent unknown although these compounds are considered to play an important role in regulating lake trophic status. To enhance identification of these compounds, a liquid chromatography (LC) method for their separation was developed. The stationary phase was porous graphitic carbon (PGC), and the mobile phases used in the gradient elution were compatible with both inductive coupled plasma atomic emission spectroscopy (ICP-AES) and electrospray ionization tandem mass spectrometry (ESI-MS/MS). With LC-ICP-AES, eight different P containing peaks could be observed in the P chromatogram indicating that at least eight different P compounds were separated. With the setup of an information dependent acquisition (IDA) with ESI-MS/MS, the mass over charge (m/z) of compounds containing a phosphate group (H2PO3−, m/z 97) could be measured and further fragmentation experiments gave additional information on the structure of almost 40 separated P compounds, several were verified to be nucleotides. ICP-AES was very suitable in the development of the LC method and allowed screening and quantification of P compounds. The presented LC-ESI-MS/MS technique was able to identify several sediment organic P compounds.
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18.
  • De Brabandere, Heidi, et al. (författare)
  • Sediment extraction and clean-up for organic phosphorus analysis by electrospray ionization tandem mass spectrometry
  • 2008
  • Ingår i: Talanta. - : Elsevier BV. - 0039-9140 .- 1873-3573. ; 74:5, s. 1175-1183
  • Tidskriftsartikel (refereegranskat)abstract
    • A method to prepare NaOH sediment extracts for organic P compound analysis with electrospray ionization tandem mass spectrometry (ESI-MS-MS) was developed on natural samples. Ion exchange, rotary evaporation and mass cut-off filtering proved to be suitable for sample preparation. Samples were analyzed with ESI-MS-MS, and reproducibility and repeatability of the method was calculated. In addition, 31P-nuclear magnetic resonance spectroscopy (31P NMR) was used to measure recovery of different P compound groups such as orthophosphate (Ortho-P), orthophosphate monoesters (Monoester-P), orthophosphate diesters (Diester-P) and pyrophosphates (Pyro-P). The developed sample preparation method resulted in an easy-to-spray liquid for the ESI-MS-MS instrumentation. The overall P recovery was 65% and 31P NMR showed that Diester-P, possibly in the form of DNA, was apparently lost through the filtering step most likely due to their size. Variances in the total intensities of the MS scans (relative standard deviation (R.S.D.) 35–54%) were for about 50% due to repeated MS runs. Covariances of the peaks in the MS spectra were calculated to be for about 30% due to the sample preparation procedure. Finally, with the ESI-MS-MS approach, 11 peaks in the mass spectra were found likely to represent phosphate containing compounds.
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19.
  • Dugopolski, Rebecca A., et al. (författare)
  • Short-term effects of a buffered alum treatment on Green Lake sediment phosphorus speciation
  • 2008
  • Ingår i: Lake and reservoir management. - : Informa UK Limited. - 1040-2381 .- 2151-5530. ; 24:2, s. 181-189
  • Tidskriftsartikel (refereegranskat)abstract
    • Green Lake, Washington, was treated with a dose of 24 mg Al/L aluminum   sulfate (alum) and sodium aluminate during March-April 2004 to reduce   dissolved phosphorus concentrations to ameliorate a variety of   eutrophication-related problems. Four sediment cores collected six   months after the alum treatment in Green Lake were used to examine the   short-term effects of alum on sediment phosphorus speciation. Peaks in   aluminum bound phosphorus (Al-P) and total aluminum (Tot-Al) were   observed in three of the four cores analyzed, resulting in an average   ratio of added Al to Al-P formed (Al:Al-P) of 112:1. By comparing this   ratio to the average ratio of similar to 11:1 found in other   alum-treated Washington lakes, it can be inferred that approximately   10% of the binding capacity of the added Al had been utilized. Assuming   a final ratio of Al:Al-P of 11:1, the added Al has the potential   capacity to bind a total of 21.6 g/m(2) of P. The amount of sediment   inorganic P that supports internal loading (Fe-P and labile-P) in the   fall of 2004 was determined to be 2.8 g/m(2). Thus the quantity of alum   added to Green Lake should be sufficient to inactivate the remaining   inorganic mobile-P and to control future P mobilization from the pool   of organic sediment P.
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21.
  • Huser, Brian, et al. (författare)
  • Longevity and effectiveness of aluminum addition to reduce sediment phosphorus release and restore lake water quality
  • 2016
  • Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 97, s. 122-132
  • Tidskriftsartikel (refereegranskat)abstract
    • 114 lakes treated with aluminum (Al) salts to reduce internal phosphorus (P) loading were analyzed to identify factors driving longevity of post-treatment water quality improvements. Lakes varied greatly in morphology, applied Al dose, and other factors that may have affected overall treatment effectiveness. Treatment longevity based on declines in epilimnetic total P (TP) concentration averaged 11 years for all lakes (range of 0-45 years). When longevity estimates were used for lakes with improved conditions through the end of measurements, average longevity increased to 15 years. Significant differences in treatment longevity between deeper, stratified lakes (mean 21 years) and shallow, polymictic lakes (mean 5.7 years) were detected, indicating factors related to lake morphology are important for treatment success. A decision tree developed using a partition model suggested Al dose, Osgood index (01, a morphological index), and watershed to lake area ratio (related to hydraulic residence time, WA:LA) were the most important variables determining treatment longevity. Multiple linear regression showed that Al dose, WA:LA, and 01 explained 47, 32 and 3% respectively of the variation in treatment longevity. Other variables (too data limited to include in the analysis) also appeared to be of importance, including sediment P content to Al dose ratios and the presence of benthic feeding fish in shallow, polymictic lakes.
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22.
  • Huser, Brian, et al. (författare)
  • Phosphorus inactivation by aluminum in Lakes Gårdsjön and Härsvatten sediment during the acidification period in Sweden
  • 2005
  • Ingår i: Canadian Journal of Fisheries and Aquatic Sciences. ; 62, s. 1702-1709
  • Tidskriftsartikel (refereegranskat)abstract
    • Acidification of lakes exposed to acid deposition is generally accompanied by a severe decrease in production (oligotrophication). In this study, we examined sediment from Lakes Gårdsjön and Härsvatten, Sweden, to determine whether sediment phosphorus (P) retention increased during the years corresponding to lake acidification. Sediment from both lakes had increases in aluminum (Al) in the upper 10 cm, and dating of Lake Gårdsjön sediment revealed that the Al increase occurred from 1950 to 2001 in this lake. The increase in Al input caused an increase inAl-bound P (Al–P) formation and overall sediment total phosphorus retention during the same period. Lake Gårdsjön received an additional 12.9 g·m–2 of Al, above preacidification background levels, that bound 1.1 g·m–2 of P and removed it from the in-lake P cycle from 1950 to 2001. A substantial portion (up to 76%) of the total external P load eventually was converted to Al–P and buried in the sediment over this period. The increase in sediment P burial due to increased formation of Al–P in systems similar to Lake Gårdsjön may have detrimental effects on nutrient cycling, and as a result, on productivity within the lake, leading to acido-oligotrophication.
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25.
  • Karlsson-Elfgren, Irene, et al. (författare)
  • Pelagic growth and colony division of Gloeotrichia echinulata in Lake Erken
  • 2005
  • Ingår i: Journal of Plankton Research. - : Oxford University Press (OUP). - 0142-7873 .- 1464-3774. ; 27:2, s. 145-151
  • Tidskriftsartikel (refereegranskat)abstract
    • Gloeotrichia echinulata colony development was monitored in Lake Erken, Sweden and studied inenclosure experiments. Significant colonial division did not occur in mesh bags, although the abundance ofthe pelagic population in the lake increased during the experimental periods. On the basis of these findings,it is suggested that circulation of G. echinulata to deeper nutrient rich water supports pelagic growth. Insupport of this, a large part of the buoyant G. echinulata colonies in Lake Erken was found at severalmeters depth. In an experiment with nutrient additions, the only treatment that favoured G. echinulatadevelopment was additions of phosphate, nitrate and iron. Trace element additions had a negative effecton the development of G. echinulata. On the basis of these findings, the nutritional requirements ofG. echinulata are discussed.
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26.
  • Karlsson-Elfgren, Irene, et al. (författare)
  • Recruitment and pelagic growth of Gloeotrichia echinulata (Chyanophyceae) in Lake Erken
  • 2003
  • Ingår i: Journal of Phycology. - : Wiley. - 0022-3646 .- 1529-8817. ; 39:6, s. 1050-1056
  • Tidskriftsartikel (refereegranskat)abstract
    • Different parameters in the life cycle of the colony forming cyanobacterium Gloeotrichia echinulata (J.E. Smith) Richter was evaluated in Lake Erken, Sweden. Recruitment of colonies from the sediments and pelagic abundance were measured during 2 years. These data were then used in a model to evaluate and estimate parameters of the life cycle. In our study, recruitment alone only contributed to a small part (<5%) of the maximum G. echinulata abundance that occurred during late summer. However, recruitment from shallow sediments forms the important seed for the pelagic population. Together with measured rates of migration from the sediment, variations in either pelagic colony division rate or pelagic residence time could explain variations in the measured abundance of G. echinulata in situ.
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27.
  • Karlsson, Magnus, et al. (författare)
  • Bottenundersökningar i Upplands, Stockholms, Södermanlands och Östergötlands skärgårdar 2008-2009. Återbesök i 1990-talets studieområden
  • 2010
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • När sedimentundersökningar av ett stort antal fjärdar i Östersjöns skärgårdsområden genomfördes under 1990-talet konstaterades att högre djurliv saknades i en majoritet av de undersökta områdenas djupare liggande bottnar och att detta sannolikt hade sin förklaring i syrgasbrist. Detta tolkades huvudsakligen som en effekt av den storskaliga övergödningen av Östersjön som orsakat en förhöjd tillförsel av organiskt material till bottnarna. I denna studie har ett antal av de fjärdar som undersöktes under 1990-talet återbesökts och nya sedimentkärnor har insamlats under 2008 och 2009. Resultaten visar att i ett antal av de fjärdar där förekomsten av laminerade (varviga) sediment var påtaglig under 1990-talet, indikerande avsaknad av bottenfauna, har det skett en övergång till bioturberade och oxiderade sediment. Förändringen av redoxförhållandena skulle kunna förklaras av en eller flera av följande faktorer 1) successiv nedbrytning av historiska utsläpp av organiskt material, 2) minskad lokal tillförsel av näringsämnen resulterande i en minskad primärproduktion och sedimentation av organiskt material, 3) bioturbation genom kolonisation av den syretåliga och invaderande havsborstmasken Marenzelleria. Förändringarnas geografiska fördelning, samvariationen med bottenfaunans sammansättning och det faktum att inga betydande förändringar noterats i den överliggande vattenmassans syrgaskoncentrationer, där sådana data funnits att tillgå, talar för att expansionen av Marenzelleria är den viktigaste orsaken bakom förändringarna.
  •  
28.
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29.
  • Karlsson, Magnus, et al. (författare)
  • Sediment studies in the Stockholm archipelago 2008
  • 2009
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • I takt med att larmrapporter om frekventa algblomningar, ökad utbredning av döda bottnar, minskande bestånd av rovfisk, förändringar i makrovegetationens sammansättning mm. under senare år duggat tätt har samhället börjat ställa krav på att åtgärder genomförs som väsentligt förbättrar miljöförhållandena i Östersjön. Ett av de mer påtagliga fenomen som kan kopplas till övergödning är den syrgasbrist som ibland uppstår längs bottnar där sedimenterande organiskt material ackumuleras och bryts ned. I många marina och limniska miljöer finns i de översta sedimentlagren längs mjukbottnar ett diversifierat och individrikt organismsamhälle. Om syrgasnivån varaktigt underskrider en kritisk nivå elimineras emellertid förutsättningarna för djurliv och det sker en succession mot bakterier som förmår leva under anaeroba förhållanden. Detta innebär att fisk och mobila bottenlevande djur lämnar området medan djur som saknar förmåga till längre förflyttningar slås ut. Ansträngda syrgasförhållanden längs bottnar har sedan lång tid tillbaka också ansetts kunna leda till en försämrad fastläggning av näringsämnet fosfor. Fosfor är ett av de näringsämnen som algerna behöver för sin tillväxt. Under ganska lång tid ansågs emellertid fosfors betydelse i Östersjön vara underordnad förekomsten av kväve, som också är ett essentiellt näringsämne för alla organismer. Senare års forskning har dock snarare pekat på motsatsen och den tidigare strategin att i första hand minska tillförseln av kväve är numer ersatt av en rekommendation att fokusera reningsåtgärderna mot fosfor. Vissa forskare anser också att det skulle vara önskvärt att på artificiell väg försöka syresätta Östersjöns bottenvatten och på så sätt öka fastläggningen av fosfor i sedimenten. Vid flera sedimentologiska undersökningar i Stockholms skärgård som genomfördes under 1990-talet förvånades man över att de påtagliga förbättringar av vattenkvaliteten som noterades i vattenmassan efter att förbättrad reningsteknik infördes under 1970-talet, resulterande i kraftigt minskad tillförsel av näringsämnen från Stockholm och Mälardalen, inte återspeglades i successivt förbättrade miljöförhållanden längs bottnarna. Tvärtom fann man att omfattande försämringar av bottenförhållandena skett under samma tidsepok som reningsverksutbyggnaden skett och att stora arealer av skärgårdens bottnar led av ansträngda syrgasförhållanden. I motsats till detta har dock regelbundna undersökningar av förekomsten av bottenlevande djur inom ramen för Stockholms stads recipient-kontrollprogram givit indikationer på en påtaglig förbättring av syrgasförhållandena i Stockholms innerskärgård under det senaste decenniet. Metodik I föreliggande studie har vi återupprepat provtagningar av sediment i flertalet av de fjärdar i Stockholms skärgård som undersöktes under 1990-talet. Vi har jämfört de resultat som erhållits från de nya undersökningarna med resultaten från undersökningarna på 1990-talet. I innerskärgården har vi också jämfört resultaten från sedimentundersökningarna med bottenfaunaundersökningar av samma områden utifrån recipientkontrollprogrammets data. Vidare har vi i fyra utvalda områden från inner-, mellan- och ytterskärgård studerat fosfors dynamik och förekomstformer i sedimenten. Förrådet av inert och rörlig fosfor har uppskattats och storleken på sedimentation, omsättning, läckage och begravning av olika fosforformer har beräknats.
  •  
30.
  • Karlsson, Magnus, et al. (författare)
  • Sediment studies in the Stockholm archipelago 2008
  • 2009
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • A clear indication of improved benthic conditions was found when sediment investigations from the 1990s were repeated in the inner Stockholm archipelago during 2008. In a majority of the investigated areas the surface sediments were oxidized and signs of bioturbation were observed. In the 1990s these areas were dominated by black and laminated surface sediments. When comparing the interpretation of sediment status versus macrozoobenthos data a clear congruence was found. The magnitude of sediment phosphorus (P) turnover in the Stockholm archipelago was closely linked to the sediment accumulation rate. Improvement of the oxygen status in the surface sediment layer have resulted in a temporary accumulation of iron (Fe) bound P. This P might reach high concentrations, and represents a withdrawal of P that otherwise would support primary production. Whether this Fe-P mainly did precipitate in the water column and did settle to the sediment, or if it formed in the oxygenated surface sediment layer due to diffusion of dissolved P and Fe from deeper sediment layers remains uncertain.
  •  
31.
  • Karlsson, O. Magnus, et al. (författare)
  • A revised semi-empirical mass balance model for phosphorus in Baltic coastal areas
  • 2014
  • Ingår i: Fundamental and Applied Limnology. - : Schweizerbart. - 1863-9135. ; 185:3-4, s. 209-221
  • Tidskriftsartikel (refereegranskat)abstract
    • A decade of research on the phosphorus dynamics in Baltic Sea coastal areas using a combination of mathematical modelling, sediment surveys and time series of water quality data from monitoring programs has led to an improved understanding of processes controlling phosphorus turnover and coastal primary production. This paper presents a revised model for phosphorus turnover in non-tidal enclosed Baltic coastal areas. Using a new dataset from 500 sediment sampling stations it was possible to quantify and develop new simplified algorithms for sedimentary processes i.e. burial and erosion that did not decrease the model's predictive power. Our results indicate that erosion of old clays can be an important primary source to phosphorus water concentrations in enclosed coastal areas. A simple laboratory experiment using Common Duckweed (Lemna minor) supports to some extent that phosphorus originating from old clays is partly bioavailable and hence may influence the trophic state in the studied areas.
  •  
32.
  • Kumblad, Linda, 1974-, et al. (författare)
  • Managing multi-functional peri-urban landscapes : Impacts of horse-keeping on water quality
  • 2023
  • Ingår i: Ambio. - : Springer. - 0044-7447 .- 1654-7209.
  • Tidskriftsartikel (refereegranskat)abstract
    • Eutrophication assessments in water management to quantify nutrient loads and identify mitigating measures seldom include the contribution from horse facilities. This may be due to lack of appropriate methods, limited resources, or the belief that the impact from horses is insignificant. However, the recreational horse sector is growing, predominantly in multi-functional peri-urban landscapes. We applied an ecosystem management approach to quantify nutrient loads from horse facilities in the Stockholm Region, Sweden. We found that horses increased the total loads with 30–40% P and 20–45% N, with average area-specific loads of 1.2 kg P and 7.6 kg N ha−1 year−1. Identified local risk factors included manure management practices, trampling severity, soil condition and closeness to water. Comparisons of assessment methods showed that literature standard values of area-specific loads and water runoff may be sufficient at the catchment level, but in small and more complex catchments, measurements and local knowledge are needed. 
  •  
33.
  •  
34.
  • Malmaeus, Mikael, et al. (författare)
  • Estimating the amount of mobile phosphorus in Baltic coastal soft sediments of central Sweden
  • 2012
  • Ingår i: Boreal environment research. - 1239-6095 .- 1797-2469. ; 17:6, s. 425-436
  • Tidskriftsartikel (refereegranskat)abstract
    • A new dataset based on 102 sediment cores was examined to estimate the amount of phosphorus (P) that will eventually be released to the water column from the Baltic coastal sediments along the Swedish coast between Öregrund and Oxelösund. Total P (P tot) concentration in the surface sediments varied between 840 and 7100 μg g -1 dry weight (dw) with an average of 1650 μg g -1 dw. In deep sediments, the P tot concentration was around 1000 μg g -1 with small variation. The difference between surface concentration and the stable, deeper, concentration represents P to be released, i.e. the mobile P. Pools of mobile P varied between 1.5 and 18.2 g m -2. Correlations between surface P tot concentrations and amounts of mobile P were strong (r 2 = 0.88). We estimate the amount of mobile P in the coastal sediments of the investigated region to be between 1000 and 4000 tonnes. Assuming a turnover time of the mobile P between three and ten years gives an average annual P release of 100-1300 tonnes yr -1.
  •  
35.
  • Milbrink, Göran, et al. (författare)
  • Large-scale and long-term decrease in fish growth following the construction of hydroelectric reservoirs
  • 2011
  • Ingår i: Canadian Journal of Fisheries and Aquatic Sciences. - 0706-652X .- 1205-7533. ; 68:12, s. 2167-2173
  • Tidskriftsartikel (refereegranskat)abstract
    • Hydroelectric reservoirs retain large volumes of water and have a global impact on sea level, elemental cycles, and biodiversity. Using data from a total of 90 historical and recent surveys in nine regulated and eight unregulated alpine and subalpine lakes, we show an additional large effect of reservoirs, i.e., that impoundment causes drastically decreased fish growth and thereby great negative consequences for inland fisheries in Scandinavia. Following a long period (40-65 years) after impoundment, the length and mass of Arctic charr (Salvelinus alpinus) of the single age class 4+ years was, on average, 35% and 72% lower, respectively, in impounded versus natural lakes in northern Scandinavia. The effect was stronger at higher altitudes and can be mitigated by addition of inorganic nutrients. We suggest that the decreased fish growth is a consequence of lowered ecosystem productivity, oligotrophication, caused by impoundment, resulting in erosion and loss of the littoral ecosystem as well as delayed flooding and leakage of nutrients from the riparian zone until after the growing season.
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36.
  •  
37.
  • Paraskova, Julia V., et al. (författare)
  • Extraction and quantification of phosphorus derived from DNA and lipids in environmental samples
  • 2013
  • Ingår i: Talanta. - : Elsevier BV. - 0039-9140 .- 1873-3573. ; 115, s. 336-341
  • Tidskriftsartikel (refereegranskat)abstract
    •  Understanding the flux and turnover of phosphorus (P) in the environment is important due to the key role P plays in eutrophication and in the ambition to find cost-effective measures to mitigate it. Orthophosphate diesters, including DNA and phospholipids (PLs), represent a potentially degradable P pool that could support future primary production and eutrophication. In this study, extraction techniques were optimized and combined with colorimetric determination of extracted P to provide a selective quantification method for DNA-P and PL-P in agricultural soil, sediment and composted manure. The proposed method is rapid and reproducible with an RSD of <10%. Recovery, evaluated by spiking the sample matrices with DNA and PL standards, was over 95% for both DNA and PLs. The method can be used for the determination of the pool size of the two organic P fractions. Results show that DNA-P comprises 3.0% by weight of the total P (TP) content in the studied soil, 10.4% in the sediment and 8.4% in the compost samples. The values for PL-P are 0.5%, 6.0% and 1.7% for soil, sediment and compost, respectively.
  •  
38.
  •  
39.
  • Paraskova, Julia V. (författare)
  • Organic phosphorus speciation in environmental samples : Method development and applications
  • 2014
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • This thesis investigates the development of new methodology for the identification and quantification of organic phosphorus compounds in environmental samples.Phosphorus is a vital element for primary production and one of the factors contributing to eutrophication. Eutrophication of aquatic systems leads to algal blooms, changes in ecological balance and deteriorating water quality. Difficulties in studying organic phosphorus stem from the fact that organic phosphorus is present in the environment in a variety of forms and each form may have different degradation and turnover time, having very different effects on eutrophication.New methods for the quantification of phosphorus derived from three groups of organic phosphorus compounds were developed. For the determination of phosphorus derived from DNA and phospholipids selective extraction was combined with digestion and colorimetric determination of the extracted phosphate. For quantification of inositol phosphates high performance liquid chromatography was coupled with tandem mass spectrometry using electrospray ionization.  The methods were applied to studying the distribution of these compounds in a small catchment and in the case of DNA-P and phospholipid-P, the degradation of the fractions in lake sediments. The studies showed that phosphorus bound to DNA, phospholipids and inositol phosphates constitute a sizeable part of the total phosphorus in different environmental samples. The phospholipid-P fraction was the smallest one, accounting for, on average, only a few percent of the total phosphorus in the sample. Inositol phosphates were most prevalent in the soils, with inositol hexakisphosphate accounting for over 10% of the total phosphorus content. The highest content of DNA-P was found in sediments and it was shown that DNA-P degrades more rapidly than phospholipid-P and therefore plays a more critical role in internal loading.
  •  
40.
  •  
41.
  • Paraskova, Julia V., et al. (författare)
  • Speciation of Inositol Phosphates in Lake Sediments by Ion-Exchange Chromatography Coupled with Mass Spectrometry, Inductively Coupled Plasma Atomic Emission Spectroscopy, and P-31 NMR Spectroscopy
  • 2015
  • Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 87:5, s. 2672-2677
  • Tidskriftsartikel (refereegranskat)abstract
    • A method for the detection and speciation of inositol phosphates (InsP(n)) in sediment samples was tested, utilizing oxalateoxalic acid extraction followed by determination by high-performance liquid chromatography coupled with tandem mass spectrometry (HPLCMS/MS) using electrospray ionization (ESI) in negative mode. The chromatographic separation was carried out using water and ammonium bicarbonate as mobile phase in gradient mode. Data acquisition under MS/MS was attained by multiple reaction monitoring. The technique provided a sensitive and selective detection of InsP(n) in sediment samples. Several forms of InsPn in the oxalateoxalic acid extracted sediment were identified. InsP(6) was the dominating form constituting 0.250 mg P/g DW (dry weight); InsP(5) and InsP(4) constituted 0.045 and 0.014 mg P/g DW, respectively. The detection limit of the LCESI-MS/MS method was 0.03 mu M InsPn, which is superior to the currently used method for the identification of InsPn, P-31 nuclear magnetic resonance spectroscopy (P-31 NMR). Additionally sample handling time was significantly reduced.
  •  
42.
  • Paraskova, Julia V., et al. (författare)
  • Turnover of DNA-P and phospholipid-P in lake sediments
  • 2014
  • Ingår i: Biogeochemistry. - : Springer Science and Business Media LLC. - 0168-2563 .- 1573-515X. ; 119:1-3, s. 361-370
  • Tidskriftsartikel (refereegranskat)abstract
    • Identifying and quantifying the forms of phosphorus (P) in lake sediments is a prerequisite for understanding lake trophic status and possible exports of P downstream. Organic P is one of the most important P forms found in the sediment, where orthophosphate diesters, including DNA and phospholipids, represent a degradable P pool that can support primary production and eutrophication. In this study, sediment cores from the eutrophic Lake Erken and the oligotrophic Lake Ånnsjön, both in steady state regarding long-term P input revealed trends in the degradation of DNA-P and PL-P with sediment depth. Comparisons were performed based on the differentiation of essentially permanent or recalcitrant P and temporary, potentially mobile P for the respective fractions. The temporary P pool was defined as the part of the total P pool calculated for values higher than the level at which the measured P concentration converged to a constant value and the recalcitrant pool was defined as the difference between the total and the temporary. The temporary diester-P pool comprised over 20 % of the total temporary P in Lake Erken and around 4 % in Lake Ånnsjön. The decrease in P concentrations with depth was more rapid for DNA-P compared to PL-P in both lakes, suggesting that DNA-P has a more prominent role in internal loading. The study shows that P mobilization potential can be different for different P fractions, which is important when assessing their contribution to internal loading of P within an aquatic system.
  •  
43.
  • Puttonen, Irma, et al. (författare)
  • Distribution and estimated release of sediment phosphorus in the northern Baltic Sea archipelagos
  • 2014
  • Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 145, s. 9-21
  • Tidskriftsartikel (refereegranskat)abstract
    • Phosphorus contents in the sediments were determined in archipelago areas of the northern Baltic Sea (Svealand in Sweden and Aland, SW Finland and W Uusimaa in Finland) during 2008-2012. Spatial and vertical distribution of phosphorus was studied by analysing sediment samples from 345 stations of different seabed substrate types. A sequential extraction method was applied to evaluate the pool of the potentially mobile phosphorus, i.e., the amount of phosphorus that can be expected to be released from sediments to water with time, and possibly support primary production. In addition, vertical distribution of immobile phosphorus forms in the sediments was used as a tool to assess phosphorus burial. The uppermost 2 cm of sediments were calculated to contain 126,000 tonnes of phosphorus in the study area covering 19,200 km(2) of the seafloor. Subtracting the assumed average background content (i.e. that assumed to be buried) of this total phosphorus content gave an estimation of 31,000-37,000 tonnes of potentially mobile phosphorus at the sediment surface. Redox sensitive iron-bound phosphorus accounts for two thirds of this pool. Compared with the total phosphorus input from the catchment of the entire Baltic Sea 29,000 tonnes in 2009 it can be concluded that the store of phosphorus that can be released with time from the sediments is large, and that internal phosphorus recycling processes thus may play a key role in phosphorus fluxes in the coastal zone. Spreading of hypoxia in the future, as recent modelling and sediment proxy results suggest, is likely to severely deteriorate the water quality, particularly in the archipelago areas where the water exchange is slow.
  •  
44.
  • Reitzel, Kasper, et al. (författare)
  • Characterization of phosphorus in sequential extracts from lake sediments using P-31 nuclear magnetic resonance spectroscopy
  • 2006
  • Ingår i: Canadian Journal of Fisheries and Aquatic Sciences. - Univ So Denmark, Inst Biol, DK-5230 Odense M, Denmark. Univ Uppsala, Dept Analyt Chem, S-75124 Uppsala, Sweden. Univ Uppsala, Dept Organ Chem, S-75124 Uppsala, Sweden. Uppsala Univ, Dept Ecol & Evolut, EBC, S-75236 Uppsala, Sweden.. - 0706-652X .- 1205-7533. ; 63:8, s. 1686-1699
  • Tidskriftsartikel (refereegranskat)abstract
    • Phosphorus (P) compounds in three different lake surface sediments were extracted by sequential P extraction and identified by P-31 nuclear magnetic resonance (P-31 NMR) spectroscopy. The extraction procedure primarily discriminates between inorganic P-binding sites but most extraction steps also contained P not reacting (nrP) with the molybdenum complex during P analyses. In all three lakes, the nrP dominated in the NaOH extracts. Nonreactive P from the dystrophic lake was dominated by potentially recalcitrant P groups such as orthophosphate monoesters, while the nrP in the two more productive lakes also contained polyphosphates, pyrophosphate, and organic P groups such as P lipids and DNA-P that may be important in remineralization and recycling to the water column. In addition, polyphosphates showed substantial dynamics in settling seston. The Humic-P pools (P associated with humic acids) showed strong signals of orthophosphate monoesters in all three lakes, which supported the assumption that P-containing humic compounds are indeed recovered in this fraction, although other organic P forms are also present. Thus, in addition to expanding the understanding of which organic P forms that are present in lake sediments, the P-31 NMR technique also demonstrated that the chemical extraction procedure may provide some quantification of recalcitrant versus labile organic P forms.
  •  
45.
  • Reitzel, Kasper, et al. (författare)
  • Degradation rates of organic phosphorus in lake sediment
  • 2007
  • Ingår i: Biogeochemistry. - Univ So Denmark, Inst Biol, DK-5230 Odense M, Denmark. Uppsala Univ, Dept Analyt Chem, S-75124 Uppsala, Sweden. Uppsala Univ, Dept Organ Chem, S-75124 Uppsala, Sweden. Uppsala Univ, Dept Limnol, S-75236 Uppsala, Sweden. : Springer Science and Business Media LLC. - 0168-2563 .- 1573-515X. ; 82:1, s. 15-28
  • Tidskriftsartikel (refereegranskat)abstract
    • Phosphorus (P) binding groups were identified in phytoplankton, settling particles, and sediment profiles by 31P NMR spectroscopy from the Swedish mesotrophic Lake Erken. The 31P NMR analysis revealed that polyphosphates and pyrophosphates were abundant in the water column, but rapidly mineralized in the sediment. Orthophosphate monoesters and teichoic acids degraded more slowly than DNA-P, polyphosphates, and P lipids. Humic acids and organic acids from phytoplankton were precipitated from the NaOH extract by acidification and identified by 31P NMR spectroscopy. The precipitated P was significantly more recalcitrant than the P compound groups remaining in solution, but does not constitute a major sink of P as it did not reach a stable concentration with depth, which indicates that it may eventually be degraded. Since P also precipitated from phytoplankton, the origin of humic-P can not be related solely to allochthonous P.
  •  
46.
  • Reitzel, Kasper, et al. (författare)
  • Diagenesis of settling seston : identity and transformations of organic phosphorus
  • 2012
  • Ingår i: Journal of Environmental Monitoring. - : Royal Society of Chemistry (RSC). - 1464-0325 .- 1464-0333. ; 14:3, s. 1098-1106
  • Tidskriftsartikel (refereegranskat)abstract
    • Solution (31)phosphorus NMR spectroscopy and sequential fractionation were used to follow diagenetic changes in phosphorus forms during decomposition of settling seston in Lake Nordborg, a shallow eutrophic lake in Denmark. In a decomposition experiment, seston released >60% of their total phosphorus during similar to 50 days incubation, although seston collected during summer contained more phosphorus and released it over a longer period compared to seston collected during spring. Seston decomposition increased concentrations of potentially bioavailable polyphosphate and phosphodiesters, but also promoted the formation of refractory phosphorus forms that might be buried permanently in the sediment. Combining these results with in situ measurements of phosphorus concentrations in lake water and sediment traps revealed that the release from settling seston plays only a minor role in the accumulation of phosphorus in the hypolimnion of Lake Nordborg.
  •  
47.
  • Reitzel, Kasper, et al. (författare)
  • Effects of aluminum treatment on phosphorus, carbon, and nitrogen distribution in lake sediment : A P-31 NMR study
  • 2006
  • Ingår i: Water Research. - Univ So Denmark, Inst Biol, DK-5230 Odense M, Denmark. Uppsala Univ, Dept Analyt Chem, S-75124 Uppsala, Sweden. Uppsala Univ, Dept Organ Chem, S-75124 Uppsala, Sweden. Uppsala Univ, EBC, Dept Ecol & Evolut, S-75236 Uppsala, Sweden. : Elsevier BV. - 0043-1354 .- 1879-2448. ; 40:4, s. 647-654
  • Tidskriftsartikel (refereegranskat)abstract
    • The effects of aluminum (Al) treatment on sediment composition of carbon (C), nitrogen (N) and phosphorus (P) were investigated in sediment representing pre- and post-treatment years in the Danish Lake Sonderby. P-31 NMR spectroscopy analysis of EDTA-NaOH extracts revealed six functional P groups. Direct effects of the Al treatment were reflected in the orthophosphate profile revealing increased amounts of AI-P in the sediment layers representing the post-treatment period, as well as changes in organic P groups due to precipitation of phytoplankton and bacteria at the time of Al addition. Furthermore, changes in phytoplankton community structure and lowered production due to the Al treatment resulted in decreased concentrations of sediment organic P groups and total C. Exponential regressions were used to describe the diagenesis of C, N, and P in the sediment. From these regressions, half-life degradation times and C, N, and P burial rates were determined. (c) 2006 Elsevier Ltd. All rights reserved.
  •  
48.
  • Rydin, Emil, et al. (författare)
  • Aluminum dose required to inactivate phosphate in lake sediments
  • 1998
  • Ingår i: WATER RESEARCH. - 0043-1354. ; 32:10, s. 2969-2976
  • Tidskriftsartikel (refereegranskat)abstract
    • Surface sediments from two shallow, eutrophic Swedish lakes with different sediment BD-P (Fe-P) content, bur similar NH4Cl-P (e.g. pore water P) concentration were treated with different amounts of aluminum sulphate at pH 6 in the laboratory to simulate t
  •  
49.
  •  
50.
  • Rydin, Emil, et al. (författare)
  • Capturing past eutrophication in coastal sediments - Towards water-quality goals
  • 2019
  • Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 221, s. 184-188
  • Tidskriftsartikel (refereegranskat)abstract
    • Bjornofjarden is a semi-enclosed brackish bay located in the Stockholm archipelago (Baltic Sea, Sweden). Anthropogenic phosphorus (P) loading to the bay over the past century has overwhelmed the largely unchanged natural supply of elements and compounds that permanently sequester P in sediments. At the same time, eutrophication has shifted surface sediments from oxic to anoxic conditions and reduced their P-retention capacity. Consequently, the release of P from anoxic sediments has become the main P source to the water column. Here we report on a long-term remediation program to reverse eutrophication in Bjornofjarden. After the implementation of measures that reduced the land-based external load to the bay, sediment-P retention was increased by mixing a solution of aluminum (Al) chloride into the anoxic and azoic sediments (> 6 m water depth) at a dose of 50 g Al/m(2), a first in a brackish environment. As a result, P accumulation in the surface sediment reached 2.0 gP/m(2) after 14 years, corresponding to 1.6 mg P/m(2)-day. This is the first time that the P accumulation rate has been determined in aquatic sediments following the addition of P-sequestering material, such as Al. The P that accumulated was dissolved P that mainly migrated from below the layer of P accumulation. The aim of the Al-addition was to sequester legacy P that had accumulated during the past century and to return Bjornofjarden to a low productivity regime, which would allow the surface sediment to become oxic and enable natural P binding by iron.
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