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  • 1.
    Berglund, Björn
    et al.
    Linköping University, Division of Medical Microbiology, Department of Clinical and Experimental Medicine, Linköping, Sweden.
    Khan, Ghazanfar Ali
    Department of Chemistry, Umeå University, Umeå, Sweden.
    Weisner, Stefan
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Ehde, Per Magnus
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Fick, Jerker
    Department of Chemistry, Umeå University, Umeå, Sweden.
    Lindgren, Per-Eric
    Linköping University, Division of Medical Microbiology, Department of Clinical and Experimental Medicine, Linköping, Sweden.
    Efficient removal of antibiotics in surface-flow constructed wetlands, with no observed impact on antibiotic resistance genes2014Inngår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 476-477, s. 29-37Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recently, there have been growing concerns about pharmaceuticals including antibiotics as environmental contaminants. Antibiotics of concentrations commonly encountered in wastewater have been suggested to affect bacterial population dynamics and to promote dissemination of antibiotic resistance. Conventional wastewater treatment processes do not always adequately remove pharmaceuticals causing environmental dissemination of low levels of these compounds. Using constructed wetlands as an additional treatment step after sewage treatment plants have been proposed as a cheap alternative to increase reduction of wastewater contaminants, however this means that the natural microbial community of the wetlands becomes exposed to elevated levels of antibiotics. In this study, experimental surface-flow wetlands in Sweden were continuously exposed to antibiotics of concentrations commonly encountered in wastewater. The aim was to assess the antibiotic removal efficiency of constructed wetlands and to evaluate the impact of low levels of antibiotics on bacterial diversity, resistance development and expression in the wetland bacterial community. Antibiotic concentrations were measured using liquid chromatography-mass spectrometry and the effect on the bacterial diversity was assessed with 16S rRNA-based denaturing gradient gel electrophoresis. Real-time PCR was used to detect and quantify antibiotic resistance genes and integrons in the wetlands, during and after the exposure period. The results indicated that the antibiotic removal efficiency of constructed wetlands was comparable to conventional wastewater treatment schemes. Furthermore, short-term treatment of the constructed wetlands with environmentally relevant concentrations (i.e. 100-2000 ng x 1(-1)) of antibiotics did not significantly affect resistance gene concentrations, suggesting that surface-flow constructed wetlands are well-suited for wastewater treatment purposes. (c) 2014 Elsevier B.V. All rights reserved.

  • 2.
    Bodin, Hristina
    et al.
    Linköping University, Linköping, Sweden.
    Mietto, Anna
    University of Padova, Legnaro, Italy.
    Ehde, Per Magnus
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Persson, Jesper
    Swedish University of Agricultural Sciences, Alnarp, Sweden.
    Weisner, Stefan
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Tracer behaviour and analysis of hydraulics in experimental free water surface wetlands2012Inngår i: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 49, s. 201-211Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Effects of inlet design and vegetation type on tracer dynamics and hydraulic performance were investigated using lithium chloride in 18 experimental free water surface wetlands. The wetlands received similar water flow but had different vegetation types: 6 emergent vegetation wetlands (EVWs), 6 submerged vegetation wetlands (SVWs) and 6 free development wetlands (FDWs). Two types of inlet designs were applied: half of each wetland vegetation type had a barrier near the inlet to help distribute incoming tracer solution, while the rest had no barrier. Residence time distribution (RTD) functions were calculated from tracer data using two techniques: method of moments and a novel Gauss modelling approach. RTD functions were used to quantify hydraulic parameters: active wetland volume (e-value), water dispersion (N-value) and hydraulic efficiency (lambda-value). For wetlands without barrier, significantly lower tracer mass recoveries were found from EVWs compared to FDWs and SVWs, signifying a risk of tracer methodological problems in small densely vegetated wetlands. These problems were minimized in wetlands with an inflow construction promoting distribution of incoming tracer solution. Compared to the method of moments, Gauss modelling seemed to produce more reliable lambda-values but less reliable N-values. Data for precise hydraulic quantification were lost by Gauss modelling, as indicated by overall lower variance in these data sets and lower mass recoveries. However, Gauss modelling may minimize uncertainties associated with lithium immobilization/mobilization. Parameters were significantly affected by the RTD data analysis method, showing that the choice of method could affect evaluation of wetland hydraulics. The experimental wetlands in this study exhibited relatively high e-values and low N-values. This was probably caused by the small size of the wetlands and low water flow velocities, emphasizing that hydraulic parameter values obtained in small experimental wetlands may not be applicable to hydraulics in larger wetlands. The method of moments revealed lower e-values from EVWs compared to SVWs and FDWs. It was indicated that lower e-values were mainly caused by vegetation volumes. This highlighted a need for regular maintenance to secure efficient treatment volume in wetlands with dense vegetation. © 2012 Elsevier B.V.

  • 3.
    Ehde, Per Magnus
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Weisner, Stefan
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Nutrient retention in constructed wetlands in an agricultural landscape in southwest Sweden2007Inngår i: 2nd International Symposium on Wetland Pollutant Dynamics and Control - WETPOL 2007: extended abstracts, Tartu: University of Tartu, 2007, s. 91-92Konferansepaper (Annet vitenskapelig)
  • 4.
    Ehde, Per Magnus
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Weisner, Stefan
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    The influence of vegetation on nitrogen retention in a long-term experimental wetland study2009Inngår i: Proceedings of the 3rd Wetland Polluntat Dynamics and Control - WETPOL 2009 - Barcelona / [ed] Josep M. Bayona & Joan García, 2009, s. 197-198Konferansepaper (Fagfellevurdert)
  • 5. Eriksson, P.G.
    et al.
    Svensson, J.M.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Carrer, M.
    Dipto. Proc. Chimici dell'Ingegneria, Université di Padova, Padua, Italy.
    Temporal changes and spatial variation of soil oxygen consumption, nitrification and denitrification rates in a tidal salt marsh of the Lagoon of Venice, Italy2003Inngår i: Estuarine, Coastal and Shelf Science, ISSN 0272-7714, E-ISSN 1096-0015, Vol. 58, nr 4, s. 861-871Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of the present study was to investigate seasonal and spatial patterns of soil oxygen consumption, nitrification, denitrification and fluxes of dissolved inorganic nitrogen (DIN) in a tidal salt marsh of the Lagoon of Venice, Italy. In the salt marsh, intact soil cores including overlying water were collected monthly at high tide from April to October in salt marsh creeks and in areas covered by the dominant vegetation, Limonium serotinum. In May, cores were also collected in areas with vegetation dominated by Juncus maritimus and Halimione portulacoides. In laboratory incubations at in situ temperature in the dark, flux rates of oxygen and DIN were monitored in the overlying water of the intact cores. 15N-nitrate was added to the overlying water and nitrification and denitrification were measured using isotope-dilution and -pairing techniques. The results show that highest soil oxygen consumption coincided with the highest water temperature in June and July. The highest denitrification rates were recorded in spring and autumn coinciding with the highest nitrate concentrations. Soil oxygen consumption and nitrification rates differed between sampling sites, but denitrification rates were similar among the different vegetation types. The highest rates were recorded in areas covered with L. serotinum. Burrowing soil macrofauna enhanced oxygen consumption, nitrification and denitrification in April and May. The data presented in this study indicate high temporal as well as spatial variations in the flux of oxygen and DIN, and nitrogen transformations in the tidal salt marshes of the Venice lagoon during the growth season. The results identify the salt marshes of the Venice lagoon as being metabolically very active ecosystems with a high capacity to process nitrogen.

  • 6.
    Fleischer, Siegfried
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Ohlsson, Lars
    Svensson, Jonas
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Våtmarkscentrum skapar viktigt nätverk2002Inngår i: Cirkulation, ISSN 1103-2855, nr 7, s. 26-27Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 7.
    Hansson, Anna
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Pedersen, Eja
    Environmental Psychology, Department of Architecture and Built Environment, Lund University, Lund, Sweden.
    Weisner, Stefan
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Landowners’ incentives for constructing wetlands in an agricultural area in south Sweden2012Inngår i: Journal of Environmental Management, ISSN 0301-4797, E-ISSN 1095-8630, Vol. 113, s. 271-278Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Eutrophication of the Baltic Sea has in Sweden led to the initiation of government schemes aiming to increase wetland areas in agricultural regions and thereby reduce nutrient transport to the sea. Landowners play a significant role as providers of this ecosystem service and are currently offered subsidies to cover their costs for constructing and maintaining wetlands. We undertook a grounded theory study, in which landowners were interviewed, aiming at identifying landowners’ incentives for constructing wetlands on their land. The study showed that adequate subsidies, additional services that the wetland could provide to the landowner, local environmental benefits, sufficient knowledge, and peers’ good experiences could encourage landowners to construct wetlands. Perceived hindrances were burdensome management, deficient knowledge, time-consuming application procedures and unclear effectiveness of nutrient reduction. The main reason for not creating a wetland, however, was that the land was classified as productive by the landowner, i.e., suitable for food production. Current schemes are directed toward landowners as individuals and based on subsidies to cover costs. We propose that landowners instead are approached as ecosystem service entrepreneurs and contracted after a tendering process based on nutrient reduction effects. This would lead to new definitions of production and may stimulate improved design and placement of wetlands.

  • 8.
    Hansson, Anna
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Pedersen, Eja
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS).
    Weisner, Stefan
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Markägares motiv för att anlägga våtmarker2010Rapport (Annet vitenskapelig)
    Abstract [sv]

    För att minska näringsläckaget från jordbruksmark via vattendrag till havet ges i Sverige bidrag till privata markägare genom olika åtgärdsprogram. Målet har varit att erhålla 12 000 hektar anlagda våtmarker 2010. Målet kommer dock inte att uppnås. Ett av skälen kan vara att markägarna har andra motiv än ekonomiska när de väljer att anlägga, eller avstå från att anlägga, en våtmark. För att öka förståelsen för markägares syn på miljö, markanvändning och vattenförvaltning och att identifiera motiv för att anlägga våtmarker genomfördes en kvalitativ studie i södra Halland. Femton markägare intervjuades och deras svar analyserades i enlighet med metoden Grundad teori. Viktigast för markägarna var Att förvalta sin mark på bästa sätt vilket innebar att mark som var odlingsbar i första hand skulle användas för det ändamålet. Lågproduktiv mark kunde komma ifråga för våtmarksanläggande, men det var inte självklart. Att ta sitt miljöansvar innebar främst att följa regelverket, men kunde också omfatta frivilliga åtgärder för miljön. Det var dock nödvändigt Att främja företagets ekonomi. Markägarna hade goda Kunskaper och insikter om jordbrukets miljöbelastning, men efterlyste Stöd och bekräftelse. Att vara missgynnad av regelverket som ansågs gynna större jordbruk och jordbruk i andra länder var allmänt. Utifrån resultatet har rekommendationer utformats inför det fortsatta arbetet med att anlägga våtmarker på privat mark.

  • 9.
    Joelsson, Arne
    et al.
    County Administrative Board of Halland, Sweden.
    Erlandsson, Gert
    Regional Development Council, Halmstad, Sweden.
    Feuerbach, Peter
    Rural Economy and Agricultural Society of Halland, Eldsberga, Sweden.
    Hansson, Anna
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Henriksson, Annika
    County Administrative Board of Halland, Sweden.
    Kindt, Torsten
    Municipality of Laholm, Sweden.
    Kling, Johan
    County Administrative Board of Halland, Sweden.
    Strand, John A.
    Rural Economy and Agricultural Society of Halland, Eldsberga, Sweden.
    Svensson, Jonas
    County Administrative Board of Halland, Sweden.
    Tollebäck, Erika
    County Administrative Board of Halland, Sweden.
    Vartia, Katarina
    County Administrative Board of Halland, Sweden.
    Weisner, Stefan
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    The Aquarius approach on mitigation of phosphorus losses2010Inngår i: 6th International Phosphorus Workshop (IPW6): Towards a sustainable control of diffuse P loss: risk, monitoring, modelling, and mitigation options, 2010, s. 164-Konferansepaper (Annet vitenskapelig)
  • 10.
    Johannesson, K.
    et al.
    Linköping University.
    Tonderski, K.S.
    Linköping University.
    Wedding, B.
    Ekologgruppen i Landskrona AB.
    Weisner, S.E.B.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Phosphorus dynamics and retention in non-point source wetlands in southern Sweden2010Inngår i: Proceedings of the 12th International Water Association International Conference on Wetland Systems for Water Pollution Control: October 4-8, 2010 Venice, Italy. Volume 1 / [ed] Fabio Masi and J. Nivala, San Giovanni Valdarno: Palombi Editori , 2010, s. 493-494Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Seven constructed wetlands receiving diffuse pollution from agricultural land in the south of Sweden were investigated with respect to water flow patterns and phosphorus (P) dynamics. P retention was positive, and correlated to P load in all wetlands. However, there was a large variation in both specific and relative retention, both between wetlands and between years. Thus, the phosphorus retention in a specific wetland is difficult to predict using simple loadretention models. The water flow was correlated to P concentrations in most wetlands; however, there were some exceptions. For instance, one wetland showed a negative relationship between water flow and P concentration during summer, which indicated that other factors than the water flow determined the dynamics of P during this season. This investigation will provide a better understanding of factors affecting phosphorus retention in constructed wetlands, with further implications for wetland research and monitoring. Furthermore, the results can assist when formulating models for phosphorus removal in wetlands receiving nonpoint source runoff.

  • 11.
    Johannesson, Karin M.
    et al.
    IFM Ecology, Linköping University, Linköping, Sweden.
    Kynkäänniemi, Pia
    Soil and Environment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Ulén, Barbro
    Soil and Environment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Weisner, Stefan E.B.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Tonderski, Karin S.
    IFM Ecology, Linköping University, Linköping, Sweden.
    Clay-bound phosphorus retention in wetlands: a catchment comparison2010Inngår i: 6th International Phosphorus Workshop (IPW6): Towards a sustainable control of diffuse P loss: risk, monitoring, modelling, and mitigation options : Book of Abstracts, 2010, s. 127-127Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Ten constructed wetlands, situated in agricultural areas in the south of Sweden, are investigated for phosphorus (P) retention and factors affecting the efficiency. These wetlands are situated in areas dominated by clay or heavy clay soils. National monitoring and estimations have shown that agricultural areas dominated by such clay soils have among the highest phosphorus losses. It has also been shown that a large proportion of P is transported in particulate form; hence, it is expected that sedimentation is the predominant P retention process in the selected wetlands. Sedimentation of clay may, however, be difficult to achieve in wetlands, and the aim of the study is to quantify the function of wetlands as sinks for the P lost from the catchments. Sedimentation and accumulation of particles are measured once a year using sedimentation plates (40×40 cm) placed on the bottom of the wetlands. Additional sedimentation traps (estimating gross sedimentation) have been placed in three of the wetlands, and those are emptied two times per year. This paper presents results for P and soil retention after the first year (in kg P ha-1 year-1), estimated by extrapolating the amount of sediment accumulated on the plates, and the content of total phosphorus (TP), to the whole wetland area. Furthermore, one wetland was selected for a detailed investigation of the effect of a vegetation filter, which in a previous study has been shown to have a positive effect on particle retention. Here, estimates of net and gross sedimentation are measured before, within and after the vegetation filter. To identify some factors of significant importance for wetland P load and retention efficiency, the statistical relationship with different wetland and catchment characteristics is analyzed. The factors included are the ratio wetland area to catchment area, average hydraulic load, and various catchment characteristics, e.g. soil type, topography, fertilization history, and soil P fractions. Since there is some uncertainty regarding sedimentation of fine clay particles (< 0.2 m), the size fractions of the accumulated sediment is determined to see whether or not the finest clay particles from the catchments settle in the wetlands. Previous studies have shown a correlation between particle size and bioavailability, where finer clay particles contain larger proportion of easily available P. Trapping the finest clay particles is therefore of particular ecological importance and needs to be further investigated.

  • 12.
    Johannesson, Karin M.
    et al.
    Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
    Kynkäänniemi, Pia
    Department of Soil and Environment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Ulén, Barbro
    Department of Soil and Environment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Weisner, Stefan
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Tonderski, Karin S.
    Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
    Phosphorus and particle retention in constructed wetlands—A catchment comparison2015Inngår i: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 80, s. 20-31Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Abstract Seven constructed wetlands (0.05–0.69 ha), situated in agricultural catchments (22–267 ha) in the south of Sweden, were studied for two years with two aims: to (i) quantify their function as sinks for particles and phosphorus (P) lost from the catchments, and (ii) investigate to what degree catchment and wetland characteristics and modeled loads (using hydrochemical catchment models) could be used to explain differences in retention between the wetlands. The wetland areas ranged from 0.04 to 0.8% of the respective catchment area, and they were situated in areas dominated by fine-textured soils with relatively high P losses and the main proportion of P transported in particulate form. Net P and particle retention were estimated during two years from annual accumulation of particles on sedimentation plates (40 × 40 cm) on the bottom of the wetlands.

    There was an annual net retention of particles and P, but with a large variation (for particles 13–108 t ha−1 yr−1 and for P 11–175 kg ha−1 yr−1), both between wetlands and between years. The difference between the two years was larger than the difference in mean P retention between the seven wetlands. There was a positive relationship between P and particle retention and three catchment factors, i.e. P status (P-AL) of agricultural soils, average slope in the catchments and the livestock density, and a negative relationship with the agricultural soil clay content. In addition, there was a positive relationship with the wetland length:width ratio. Contrary to expectations, neither the modeled hydraulic load nor P load was significantly correlated with the measured particle and P retention. There was also a positive relationship between P concentration in the sediment and soil P status in the catchment. The results imply that considerable errors are introduced when down-scaling modeled regional nutrient losses to estimate the P loads to small wetlands in agriculturally dominated catchments. A more qualitative approach, using catchment characteristics for identification of hot-spot fields, may be equally good to identify suitable locations for constructed wetlands to reduce diffuse P loads. © 2014 Elsevier B.V.

  • 13.
    Johannesson, Karin
    et al.
    Institutionen för fysik, kemi och biologi, Ekologi, Linköpings universitet, Linköping, Sverige.
    Tonderski, Karin
    Institutionen för fysik, kemi och biologi, Ekologi, Linköpings universitet, Linköping, Sverige.
    Wedding, Bengt
    Ekologgruppen i Landskrona AB, Landskrona, Sverige.
    Ehde, Per Magnus
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Weisner, Stefan
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Phosphorus load variations and retention in non-point source wetlands in southern Sweden2011Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Data from seven constructed wetlands receiving runoff from agricultural catchments in the south of Sweden were investigated with respect to phosphorus (P) retention. The seven wetlands differed in size (0.22-2 ha), design, land use and catchment characteristics. The hydraulic load varied between 7 and 725 m yr-1, which reflect the different geographical and hydrological conditions. The overall aim of this study was to increase the understanding of how water flow and inflow P concentration varations affect the P retention in constructed wetlands receiving runoff from arable land. Water flow was measured continuously, and time or flow proportional water samples were taken. Grab samples were taken during high flow periods and also to supplement the automatic water sampling. P retention varied between wetlands, from 1 to 58 kg ha-1 yr-1, and was correlated to the P load (R2=0.9, p<0.05). P retention in the wetlands varied strongly between years, and negative retention was recorded for some years and wetlands. When investigating monthly retention for each wetland, release of P corresponded to either high flow or possible anoxic conditions during low-flow periods in summer or during winter when ice covered the wetlands. Analyses of grab samples revealed a relationship between TP concentration and water flow for most wetlands. In some wetlands, P was transported mainly as particulate P (PP), but in other wetlands, soluble P was the dominating form in both inflow and outflow. Incoming concentrations varied greatly between wetlands (1-2000 μg l-1) which reflected the different catchment characteristics, e.g. land use, soil type and topography.

  • 14.
    Kallner Bastviken, Sofia
    et al.
    IFM Biology, Linköping University, Campus Valla, Sweden.
    Weisner, Stefan E.B.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Thiere, Geraldine
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Svensson, Jonas M.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Ehde, Per Magnus
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Tonderski, Karin S.
    IFM Biology, Linköping University, Campus Valla, Sweden.
    Effects of vegetation and hydraulic load on seasonal nitrate removal in treatment wetlands2009Inngår i: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 35, nr 5, s. 946-952Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Optimising nitrate removal and identifying critical factors for nitrate removal in wetlands is an important environmental task in the effort to achieve better surface water quality. In this study, eighteen free water surface wetlands with similar shape and size (22 m2 each) received groundwater with a high nitrate-N concentration (about 11 mg l−1). The effects of two hydraulic loads, 0.13 m d−1 and 0.39 m d−1, and three vegetation types – emergent, submersed and freely developing vegetation – on the nitrate-N removal were investigated through mass inflow and outflow measurements.

    No significant difference in nitrate removal between the different hydraulic loads could be detected. Significantly higher area-specific nitrate removal and first-order area-based rate coefficients were found in the basins with emergent vegetation, with no difference between the basins with submersed and freely developing vegetation. The nitrate-N removal increased as the wetlands matured and the vegetation grew denser, emphasizing the role of dense emergent vegetation for nitrate removal at high nitrate concentrations.

  • 15. Milenkovski, S
    et al.
    Thiere, Geraldine
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Samuelsson, K
    Weisner, Stefan
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Berglund, O
    Lindgren, P-E
    Denitrification in constructed wetlands in southern Sweden2007Inngår i: 2nd International Symposium on Wetland Pollutant Dynamics and Control - WETPOL 2007: Extended abstracts / [ed] Ülo Mander, Margit Kõiv, Christina Vohla, Institute of Geography, 2007, s. 220-222Konferansepaper (Annet vitenskapelig)
  • 16.
    Milenkovski, Susann
    et al.
    Department of Chemical Ecology/Ecotoxicology, Lund University, Lund, Sweden.
    Berglund, Olof
    Department of Chemical Ecology/Ecotoxicology, Lund University, Lund, Sweden.
    Thiere, Geraldine
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Samuelsson, Kristina
    Swedish County Administrative Board, Länsstyrelsen Kalmar län, Kalmar, Sweden.
    Weisner, Stefan
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Lindgren, Per-Eric
    Department of Clinical and Experimental Medicine, Division of Medical Microbiology, Linköping University, Linköping, Sweden.
    Composition of denitrifying bacterial enzyme genes nirS, nirK and nosZ in constructed wetlandsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    In this study the composition of the denitrifying bacterial community among constructed wetlands in agricultural areas was investigated. Thirty-two constructed wetlands located in Southern Sweden were surveyed, and biofilm samples from each were analyzed by applying denaturing gradient gel electrophoresis, to investigate the community composition of the three denitrifying bacterial enzyme genes nirK, nirS and nosZ. The DNA sequences of the enzyme genes were compared to known DNA sequences in GeneBank using BLAST. The results of the denitrifying bacterial enzyme genes indicated that these habitats may harbour a heterogeneous denitrifying bacterial community. Individual analysis of the enzyme genes revealed that nirS was more heterogeneous than both nirK and nosZ. Most sequences from the present study clustered with known sequences from species belonging to the group of α-Proteobacteria, and to a lesser extent with β- Proteobacteria and γ-Proteobacteria, and only nirS clustered with a member of gram-positive bacteria.

  • 17.
    Milenkovski, Susann
    et al.
    Department of Chemical Ecology/Ecotoxicology, Lund University, Lund, Sweden.
    Thiere, Geraldine
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Weisner, Stefan
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Berglund, Olof
    Department of Chemical Ecology/Ecotoxicology, Lund University, Lund, Sweden.
    Lindgren, Per-Eric
    Department of Clinical and Experimental Medicine, Division of Medical Microbiology, Linköping University, Linköping, Sweden.
    Variation of eubacterial and denitrifying bacterial biofilm communities among constructed wetlandsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Bacteria play important roles in the transformation of nutrients in wetlands, but few studies have examined parameters affecting variation in bacterial community composition between wetlands. We compared the composition of eubacterial and denitrifying bacterial biofilm communities in 32 agricultural constructed wetlands in southern Sweden, and the extent to which wetland environmental parameters could explain the observed variation. Structure and richness of the eubacterial 16S rRNA gene and three denitrifying bacterial enzyme genes (nirK, nirS and nosZ), analysed by molecular fingerprinting methods, varied among the constructed wetlands, which could be partly explained by different environmental parameters. Results from the enzyme gene analyses were also compared to determine whether the practice of using a single denitrifying bacterial gene could characterize the overall community composition of denitrifying bacteria. We found that nirK was more diverse than both nirS and the nosZ, and the band structure and richness of the three genes were not related to the sam environmental parameters. This suggests that using a single enzyme gene may not suffice to characterize the community composition of denitrifying bacteria in constructed agricultural wetlands.

  • 18.
    Persson, Anders
    et al.
    Department of Ecology, Limnology, Ecology Building, Lund, Sweden.
    Svensson, Jonas M.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Effects of benthivorous fish on biogeochemical processes in lake sediments2006Inngår i: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 51, nr 7, s. 1298-1309Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    1. Studies of aquatic environments have shown that community organisation may strongly affect ecosystem functioning. One common phenomenon is a change in nutrient level following a shift in the fish community composition. Although several hypotheses have been suggested, there is no consensus on which mechanisms are involved. Our study evaluated indirect effects of benthivorous fish on the biogeochemical processes at the sediment-water interface separately from direct effects caused by nutrient excretion or sediment resuspension.

    2. We assigned field enclosures to three treatments representing typical pond communities; without fish, addition of approximately 10 small tench or addition of one large bream. After one summer, we monitored the water chemistry, benthic invertebrates and periphyton in the enclosures and sampled sediment cores for laboratory analysis of biochemical process rates (oxygen, phosphorus and nitrogen exchange between sediment and water, and denitrification rate).

    3. Fish had strong negative effects on benthic invertebrates, but weaker effects on periphyton, organic content and porosity of the sediment. Moreover, there were significant positive fish effects on both phosphorus and nitrogen concentrations in the water. However, there were no general treatment effects on sediment processes that could explain the treatment effects on water chemistry in the enclosures.

    4. Hence, overall treatment effects attenuated along the chain of interactions. We conclude that the observed effect of benthic fish on water chemistry was probably because of direct effects on nutrient excretion or resuspension of sediment. The similarity between bream and tench treatments suggests large niche complementarity despite their different habitat preferences.

  • 19.
    Persson, Anders
    et al.
    Department of Ecology, Limnology, Lund University, Lund, Sweden.
    Svensson, Jonas M.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Vertical distribution of benthic community responses to fish predators, and effects on algae and suspended material2006Inngår i: Aquatic Ecology, ISSN 1386-2588, E-ISSN 1573-5125, Vol. 40, nr 1, s. 85-95Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The vertical positioning of benthic invertebrates should be a trade-off between the risky, but productive, sediment surface and the safer, but physiologically harsher, conditions deeper down in the sediment. This is because the foraging efficiency of benthic fish decreases with sediment depth, whereas the sediment surface is generally better oxygenated and has a higher resource quality than lower layers. We studied how two benthic fish predators, bream (Abramis brama) and ruffe (Gymnocephalus cernuus), affected the community composition and vertical distribution of benthos, and their indirect effects on algae and suspended material, in field enclosures. Whereas bream had significant effects on the density, composition and distribution of the benthos, ruffe had no such effects. The total benthos biomass in bream treatments was an-order of magnitude lower in the upper sediment layer (0-1 cm) and three times lower in the middle layer (1-3 cm) than in the controls, whereas there were no significant effects in the deepest layer (3-10 cm). Bivalves persisted in the deepest layer although their density was reduced in shallow sediment, whereas gastropods faced the risk of local extinction in the presence of bream. As indirect effects, small-bodied cladocerans, phytoplankton, periphyton and both organic and inorganic suspended material were higher in the bream treatments. We conclude that the impact of bream diminished substantially with increasing sediment depth, enabling invertebrates to survive in the sediment and to persist in the presence of bream. However, there were no indications of any group adjusting their vertical position behaviourally as a response to predation threat.

  • 20.
    Persson, Jesper
    et al.
    Sveriges Lantbruksuniversitet.
    Weisner, Stefan
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Integrera teknik och biologi vid utformning och anläggning2002Inngår i: Våtmarksboken: Skapande och nyttjande av värdefulla våtmarker / [ed] Karin Tonderski, Stefan Weisner, Jan Landin, Hans Oscarsson, Göteborg: Vattenstrategiska forskningsprogrammet (VASTRA) , 2002, s. 252-270Kapittel i bok, del av antologi (Fagfellevurdert)
  • 21.
    Strand, John A.
    et al.
    Hushållningssällskapet i Halland.
    Feuerbach, Peter
    Hushållningssällskapet i Halland.
    Svensson, Jonas
    Länsstyrelsen i Hallands län.
    Vartia, Katarina
    Länsstyrelsen i Hallands län.
    Kindt, Torsten
    Laholms kommun.
    Kling, Johan
    Havs- och vattenmyndigheten.
    Henriksson, Annika
    Agellus.
    Joelsson, Arne
    Länsstyrelsen i Hallands län.
    Edenman, Gunnar
    Aquarius-projektet.
    Hansson, Anna
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Weisner, Stefan
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Erlandsson, Gert
    Region Halland.
    Markägare som vattenförvaltare i ett förändrat klimat2012Rapport (Annet vitenskapelig)
  • 22.
    Strand, John A.
    et al.
    Hushållningssällskapet Halland.
    Weisner, Stefan
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Kävlingeåprojektet – utvärdering av etapp I-III: Rapport på uppdrag av Programberedningen för Kävlingeåprojektet2010Rapport (Annet vitenskapelig)
  • 23.
    Strand, John A.
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Weisner, Stefan
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Vegetationsförändringar i Vänern - steg två: Projektplan för att utreda orsaken till igenbuskningen av skär och stränder samt dynamik hos vattenvegetationen2002Rapport (Annet vitenskapelig)
  • 24.
    Strand, John A.
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Weisner, Stefan E. B.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Combating eutrophication of the sea and enhancing biodiversity of the agricultural landscape: experiences from wetland creation in Sweden2011Konferansepaper (Annet vitenskapelig)
  • 25.
    Strand, John A.
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Weisner, Stefan E B
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Effects of wetland construction on nitrogen transport and species richness in the agricultural landscape – experiences from Sweden2013Inngår i: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 56, s. 14-25Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Constructed wetlands, have been used to decrease nitrogen transport from agricultural catchments to the coast of Sweden, while simultaneously contributing to increased species richness in the landscape. The purpose of this paper is to compile and evaluate data that have been produced in Sweden during some 20 years of using constructed wetlands as an environmental tool. To evaluate effects of different stated objectives for constructed wetlands within different national support systems we focus on nitrogen removal and bird and amphibian species richness. Continuous automatic water sampling for nitrogen removal measurements, during 1.5 to 10 years, has been performed in 7 constructed wetlands located in agricultural catchments in southern Sweden. Nitrogen removal per wetland area varied between wetlands but the results imply that an annual removal of at least 1000. kg. N per ha wetland area can be achieved in individual wetlands. Data from the long-term monitoring of the 7 wetlands, together with nitrogen removal data in the literature, were used to model >150 randomly selected constructed wetlands. According to the modeling, the nitrogen removal per created wetland area varied markedly between different wetland creation programs and was generally considerably lower compared to what can be achieved in individual wetlands. Cost-efficiency of nitrogen removal in wetland creation programs can be increased considerably with improved planning and if other desired benefits (e.g. species richness) contribute to share the costs for wetland creation. The effects of constructed wetlands in Sweden on species number and populations of wetland birds and amphibians were large enough to positively affect the occurrence of species in the national red list, i.e. on a national population level. Species richness of wetland breeding birds in the constructed wetlands were relatively stable after 13 years, but different functional groups had very different succession pattern. The mean maximum breeding bird species number in the wetlands occurred after 3.8 years. Wetland birds and amphibians colonized constructed wetlands irrespective of the original objective of the wetland (nitrogen removal or biodiversity). However, some amphibian species showed preference for biodiversity wetlands. There were clear effects of wetland construction on the regional populations of non-wetland bird species. The maximum species number for a given wetland size was found to be higher than previously reported. The analyses show that wetland construction can be a cost effective method for decreasing transport of diffuse pollution from arable land, and that the wetlands are important for the species numbers and population sizes on all spatial scales. © 2013 Elsevier B.V.

  • 26.
    Strand, John A.
    et al.
    The Rural Economy and Agricultural Society of Halland, Lilla Boslid, Eldsberga, Sweden .
    Weisner, Stefan E.B.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Phenotypic plasticity – contrasting species-specific traits induced by identical environmental constraints2004Inngår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 163, nr 3, s. 449-451Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Can it be assumed that a specific environmental constraint imposed on different species leads to a convergence in, for example, morphology? A phenotype expressed in response to external stimuli (e.g. size-reduction in response to mechanical stress) should be adaptive regardless of species – this is largely intuitive, but has been poorly studied. In this issue (pp. 651–660), Puijalon & Bornette reveal exciting new data that suggest that phenotypic plastic responses to identical environmental constraints may indeed be species-specific (Puijalon & Bornette, 2004).

  • 27.
    Svensson, Jonas
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Fleischer, Siegfried
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Rosenqvist, Torsten
    Högskolan i Halmstad.
    Stibe, Lars
    Länsstyrelsen Halland.
    Pansar, Joakim
    Högskolan i Halmstad.
    Ekologisk dagvattenhantering i Halmstad2002Bok (Annet vitenskapelig)
    Abstract [sv]

    Rapporten sammanställer erfarenheter med ekologisk dagvattenhantering i Halmstad samt uppföljningsinsatser av specifika objekt för bedömning av avskiljningseffektivitet av metaller, näringsämnen och andra vattenkemiska substanser.

  • 28.
    Svensson, Jonas M.
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Strand, John A.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Sahlén, Göran
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Weisner, Stefan E.B.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Rikare mångfald och mindre kväve: Utvärdering av våtmarker skapade med stöd av lokala investeringsprogram och landsbygdsutvecklingsstöd2004Bok (Annet vitenskapelig)
    Abstract [sv]

    På uppdrag av Naturvårdsverket och Jordbruksverket har Våtmarkscentrum, Högskolan i Halmstad, utvärderat svenska våtmarker anlagda med landsbygdsutvecklingsstöd, LBU-stöd (Miva, projektstöd och Lmiva utan projektstöd) respektive våtmarker anlagda inom lokala investeringsprogram (LIP) avseende näringsretention och biologisk mångfald. Resultaten från utvärderingen redovisas separat för de fyra olika grupperna/kategorierna av anlagda våtmarker enligt nedan (fetstil anger kategorihänvisning i text, tabeller och figurer):

    • Våtmarker anlagda med anläggningsstöd inom Lokala investeringsprogram 1998 - 2002, LIP.

    • Våtmarker anlagda med anläggningsstöd inom LBU-projektstöd (dessa våtmarker får vanligen även skötselstöd, Lmiva), 2000 - 2002.

    • Våtmarker anlagda 1996-1999, utan anläggningsstöd men med skötselstöd (Miljöstöd), Miva.

    • Våtmarker anlagda från år 2000 - , utan anläggningsstöd men med skötselstöd (LBU-våtmarker som endast får skötselersättning), Lmiva.

    Syftet har främst varit att utvärdera och jämföra hur våtmarksanläggning inom olika stödformer har bidragit till minskad övergödning och ökad biologisk mångfald. Syftet har alltså inte varit att utvärdera enskilda våtmarker utan att ge en helhetsbild för olika stödformer och regioner. Därför har det varit nödvändigt att basera utvärderingen på data för ett stort antal våtmarker. Detta innebär att utförliga mätningar ej kunnat genomföras inom de enskilda objekten. Närsaltsretention har därför beräknats baserat på modeller och biologisk mångfald har undersökts genom att trollsländor använts som indikatorgrupp.

    Inom uppdraget har, med jordbruksstöd, registrerats information om totalt 908 våtmarksobjekt om totalt 2860 ha ersatt yta fördelat på 1815 ha Miva, 920 ha projektstöd och 125 ha Lmiva utan projektstöd. Totalt registrerade våtmarker med stöd från LIP är 274 st, omfattande 439 ha.

    Kompletterande fältstudier har utförts i drygt 100 st våtmarker. Främst är det resultaten från dessa våtmarker som sammanfattas nedan...

  • 29.
    Thiere, G.
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Stadmark, J.
    Lund University.
    Weisner, Stefan
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Retention capacity achievements versus climate gas emission by constructed agricultural wetlands2007Inngår i: 2nd International Symposium on Wetland Pollutant Dynamics and Control - WETPOL 2007: Extended abstracts / [ed] Ülo Mander, Margit Kõiv, Christina Vohla, Institute of Geography, University of Tartu , 2007, s. 302-304Konferansepaper (Annet vitenskapelig)
  • 30.
    Thiere, Geraldine
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Biodiversity and ecosystem functioning in created agricultural wetlands2009Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This doctoral dissertation was produced in a cooperation between Halmstad University (Wetland Research Centre, School of Business and Engineering) and Lund University (Limnology & Marine Biology, Department of Ecology).

    Abstract . Wetland creation at large, regional scales is implemented as a measure to abate the biodiversity loss in agricultural landscapes and the eutrophication of watersheds and coastal areas by non-point source nutrient pollution (mainly nitrogen). The consequences of creating many new wetlands for biodiversity conservation and nutrient reten- tion (ecosystem functioning) in agricultural landscapes are still relatively unknown, both on local (per wetland) and regional (per landscape) scales. In Sweden, wetland creation has progressed already since the 1990s, and by now larger numbers of created wetlands are present, mainly in the intensively farmed landscapes of southwestern Sweden. This thesis aimed to investigate the following aspects in these systems: (i) their large-scale effects on biodiversity, (ii) their functional diversity of bacterial denitrifiers, (iii) the abiotic and biotic influences on wetland ecosystem functioning, (iv) the potential for biodiversity-function links, and (v) the potential for functional links and joint functioning.(i) Created wetlands hosted diverse assemblages of macroinvertebrates and plants. They maintained a similar com- position and diversity as natural ponds in agricultural landscapes. The environmental conditions per wetland did hardly affect macroinvertebrate and plant assemblages, and the prerequisites for nutrient retention did neither. In landscapes were wetland creation efforts had increased the total density of small water bodies by more than 30%, macroinver- tebrate diversity of created wetlands was facilitated on both local and regional scales. (ii) Diverse communities of denitrifying bacteria with the capacity for conducting different denitrification steps (functional types) were present in all investigated wetlands. The richness of denitrifying bacteria communities was affected by nitrate concentration and hydraulic loading rate, which may potentially be relevant for the nitrogen retention function of created wetlands. The diversity across different functional types of bacterial denitrifiers increased with nitrate concentration. (iii) Both abiotic and biotic factors influenced ecosystem functions of created wetlands. Variation in nitrogen retention was associated to nitrate load, but even to vegetation parameters. In wetlands with constant nitrate load, planted emergent vegetation facilitated nitrogen retention compared to other vegetation types. In wetlands with variable loads, nitrogen retention was facilitated if nitrate load was high and many different vegetation types were present; nitrogen load could explain the majority of the variation in nitrogen retention compared to vegetation parameters. Phosporus retention of created wetlands was best explained by vegetation parameters. Litter decomposition was inhibited at high nitrate to phosphorus ratios. Methane production increased with age and decreased with plant cover. (iv) Biodiversity may facilitate wetland ecosystem functions, particularly in dynamic wetland ecosystems. Nitrogen retention increased with vegetation type diversity, phosphorus retention capacity with plant richness, and litter decomposition with macroinvertebrate diversity. (v) Created wetlands have the capacity of sustaining several parallel ecosystem services. Some wetland functions were coupled; nitrogen retention increased with fast litter decomposition. On the other hand, methane emission and nitro- gen retention were independent of each other, as were nitrogen and phosphorus retention.In conclusion, created wetlands have the potential to at least partly abate the lost biodiversity and multifunctionality caused by the past extensive destruction of natural wetlands in agricultural landscapes.

  • 31.
    Thiere, Geraldine
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Milenkovski, Susann
    Department of Ecology, Ecology Building, Lund University, Lund, Sweden.
    Lindgren, Per-Eric
    Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
    Sahlén, Göran
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS).
    Berglund, Olof
    Department of Ecology, Ecology Building, Lund University, Lund, Sweden.
    Weisner, Stefan E.B.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Wetland creation in agricultural landscapes: Biodiversity benefits on local and regional scales2009Inngår i: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 142, nr 5, s. 964-973Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wetland creation aiming at a simultaneous increase in nutrient retention and species diversity in agricultural landscapes has recently become applied as a catchment-scale compensation measure for past wetland losses. Here, we evaluate if, and to what extend, dual-purpose wetlands benefit local and regional diversity of agricultural landscapes. We analysed composition and α, β, and γ diversity of aquatic macroinvertebrate assemblages among dual-purpose wetlands in an agricultural region in southwest Sweden in relation to local (water quality, wetland morphology, succession stage, proximity to other aquatic habitats) and landscape parameters (regional connectivity, wetland density). Diversity of mature agricultural ponds was used as a standard to evaluate the value of dual-purpose wetlands. Dual-purpose wetlands sustained α, β, and γ diversity similar to that of natural lentic water bodies in agricultural landscapes in the region and elsewhere. Over 80% of the overall species richness was attributed to β diversity, and each created wetland contributed to overall species accumulation. Ecosystem parameters explained 19% of the compositional variation among assemblages, but were only marginally related to diversity. Wetland density promoted α and γ diversity, while spatial heterogeneity (β) remained equally high, independent of wetland density. Our results indicate that catchment-scale wetland creation for simultaneous retention and diversity purposes benefits the biodiversity of agricultural landscapes, particularly if the density of aquatic habitats is increased by at least 30%.

  • 32.
    Thiere, Geraldine
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Schulz, Ralf
    Department of Zoology, University of Stellenbosch, South Africa.
    Runoff simulation with particle-associated azinphosmethyl in multispecies stream microcosms: implications for the field2004Inngår i: Environmental Toxicology and Chemistry, ISSN 0730-7268, E-ISSN 1552-8618, Vol. 23, nr 8, s. 1984-1990Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigated the acute (5 d) effects of particle-associated azinphosmethyl (AZP) in multispecies microcosms and assessed the results in the context to data obtained from a parallel field study undertaken in the Lourens River, South Africa. A runoff simulation was carried out in stream microcosms containing the macroinvertebrate fauna of an uncontaminated Lourens River site exposed to particle-associated AZP (control and 200, 1,000, 5,000, 20,000 μg/kg; three replicates each) for 1 h. Measured AZP concentrations in filtered microcosm water resulted in the following values: Not detectable (control) and 0.03, 0.2, 1.1, and 6.9 μg/L, respectively. The two highest treatments resulted in significantly (analysis of variance [ANOVA]) reduced total numbers of individuals, while the number of taxa was affected in the 20,000 μg/kg treatment only. A comparison with previous data suggests that observed effects partly resulted from particle-associated AZP. Particularly affected were six out of 14 macroinvertebrate taxa such as mayfly and stonefly taxa. In parallel, the distribution of macroinvertebrates at a pesticide-free and a contaminated stretch of the Lourens River was monitored five times during the spraying season in 2001 and 2002. Out of the 14 core taxa found in the microcosm study as well as in the field approach, 10 showed comparable reactions in the microcosm experiment and in their field distribution; they were either classified as affected or unaffected in both studies. Thus, we conclude that particle-associated AZP has the potential to affect the invertebrate community structure of the Lourens River and that microcosm studies employing field-relevant exposure scenarios may be valuable for a local risk assessment of pesticide-related community disruptions in the Lourens River.

  • 33.
    Thiere, Geraldine
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Schulz, Ralf
    Department of Zoology, University of Stellenbosch, South Africa .
    Runoff-related agricultural impact in relation to macroinvertebrate communities of the Lourens River, South Africa2004Inngår i: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 38, nr 13, s. 3092-3102Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A field study at the Lourens River, South Africa, was undertaken during the pesticide application period between November 2001 and January 2002 in order to investigate the potential relation of agricultural pollution to the aquatic macroinvertebrate fauna. The upper regions of the Lourens River were free of contamination (LR1), whereas subsequent stretches flowing through a 400-ha orchard area (LR2) received transient insecticide peaks. Continuously operating suspended-particle samplers as well as flood samplers operating during runoff events were used to measure pesticide contamination. In addition, various physicochemical and morphological parameters were examined. A survey of the macroinvertebrate communities associated with the rocky substrates was carried out every three weeks. Community indices were calculated using the South African Scoring System (SASS 5) for bioassessment of water quality in rivers.

    The two sites differed in pesticide pollution as well as in average turbidity levels (LR1 5.5 mg/L; LR2 64.3 mg/L), but were similar in bottom substrate composition and most other abiotic factors. At the downstream site (LR2), pesticide values of 0.05 μg/L azinphos-methyl in water as well as 49 μg/kg azinphos-methyl, 94 μg/kg chlorpyrifos and 122 μg/kg total endosulfan in suspended particles were found during runoff conditions. The macroinvertebrate communities of the two sampling sites were similar in terms of number of total individuals, but differed significantly (ANOVA) in average number of taxa (LR1 11.7, LR2 8.9). Seven out of 17 investigated taxa occurred in significantly reduced numbers or were even absent at the downstream site LR2. The community characteristics determined by SASS 5 showed a significantly less sensitive community structure at the downstream site (TS 41; ASPT 4.6), indicating continuously lower water quality compared to site LR1 (TS 80; ASPT 6.9). It is concluded that the Lourens River macroinvertebrate communities are affected by agricultural pollution, with pesticides and increased turbidity as the most important stressors.

  • 34.
    Thiere, Geraldine
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Stadmark, Johanna
    Department of Ecology, Limnology, Lund University, Ecology Building, SE-223 62 Lund, Sweden.
    Weisner, Stefan E. B.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Nitrogen retention versus methane emission: Environmental benefits and risks of large-scale wetland creation2011Inngår i: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 37, nr 1, s. 6-15Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Coastal eutrophication by nutrient fluxes from agricultural land to marine recipients is presently combated by measures such as the implementation of watershed-scale wetland creation programs aimed at nitrogen removal. Such created agricultural wetlands – termed ‘nitrogen farming wetlands’ (NFWs) – receive nitrogen (N) loads predominantly as nitrate, facilitating N removal by denitrification. However, the conversion of agricultural soils into waterlogged wetland area is likely to increase climate gas emissions, particularly methane (CH4). There is thus a need to evaluate the benefits and risks of wetland creation at a large, watershed-scale. Here we investigate N retention and CH4 emission originating from watershed-scale wetland creation in South Sweden, the relation between both processes, and how CH4 emission depends on individual wetland parameters. We combine data from intensively studied reference wetlands with an extensive wetland survey to predict N retention and CH4 emission with simple models, to estimate the overall process rates (large-scale effects) as well as spatial variation among individual NFWs. We show that watershed-scale wetland creation serves targeted environmental objectives (N retention), and that CH4 emission is comparably low. Environmental benefit and risk of individual wetlands were not correlated, and may thus be managed independently. High cover of aquatic plants was the most important wetland property that suppressed CH4 net production, potentially facilitating N retention simultaneously. Further, differences between wetlands in water temperature and wetland age seemed to contribute to differences in CH4 net production. The nationally planned wetland creation (12,000 ha) could make a significant contribution to the targeted reduction of N fluxes (up to 27% of the Swedish environmental objective), at an environmental risk equaling 0.04% of the national anthropogenic climate gas emission.

  • 35.
    Thiere, Geraldine
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Weisner, Stefan
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Biodiversity and ecosystem functioning in created agricultural wetlands.: Key note presentation.2009Inngår i: 3rd Wetland Pollutant Dynamics and Control - WETPOL2009- Barcelona / [ed] Josep M. Bayona & Joan García, 2009, s. 29-30Konferansepaper (Fagfellevurdert)
  • 36.
    Tonderski, Karin S.
    et al.
    IFM div. Ecology, Linkoping University.
    Svensson, J. M.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Ekstam, Börje
    Högskolan i Kalmar.
    Eriksson, Peder
    Länsstyrelsen i Örebro län.
    Fleischer, Siegfried
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Herrmann, Jan
    Högskolan i Kalmar.
    Sahlén, Göran
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Weisner, Stefan E.B.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Våtmarker: Närsaltsfällor och/eller myllrande mångfald?2003Inngår i: Vatten: tidskrift för vattenvård, ISSN 0042-2886, Vol. 59, nr 4, s. 259-270Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper summarizes the state-of-the-art with respect to wetlands for nutrient removal and biodiversity enhancement, as expressed at a research workshop in December 2002. In the end of 2002, 260 and 884 wetlands had been constructed in Sweden with subsidies from LIP and the European Union, respectively. Most frequently, the aims were to remove nutrients from water and enhance biodiversity. The question raised is if we know how to design multifunctional wetlands. Should a wetland be deep or shallow, with or without macrophytes to be an efficient nutrient sink? Diverging opinions are presented, but generally it appears that fairly shallow wetlands at least partly covered by emergent macrophytes are favourable. The importance of extreme high flows and hydraulic short-circuiting is highlighted, and Danish and Norwegian approaches to wetlands construction are presented. Also, there is a risk that nutrient retaining wetlands develop a fairly trivial flora and fauna unless special care is taken. Intentional establishment of desirable and less common species, as well as creation of a variation of depth gradients to favour such species are such measures. Others are allowing for water level variations, as well as vegetation management such as grazing and harvesting.

  • 37.
    Tonderski, Karin
    et al.
    Department of Physics and Measurement Technology, Biology and Chemstry, Linköping University.
    Weisner, Stefan
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Ecological biotechnology in wetlands?2004Inngår i: Water research – what’s next? / [ed] Birgitta Johansson, Stockholm: Forskningsrådet Formas , 2004, s. 41-43Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 38.
    Tonderski, Karin
    et al.
    IFM, Linköpings Universitet.
    Weisner, Stefan E. B.Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.Landin, JanIFM, Linköpings Universitet.Oscarsson, HansMiljöskyddsenheten, Länsstyrelsen Västra Götaland.
    Våtmarksboken: Skapande och nyttjande av värdefulla våtmarker2002Collection/Antologi (Annet (populærvitenskap, debatt, mm))
  • 39.
    Vretare Strand, Viveka
    et al.
    Limnology, Department of Ecology, Lund University, Sweden.
    Weisner, Stefan E.B.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Interactive effects of pressurized ventilation, water depth and substrate conditions on Phragmites australis2002Inngår i: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 131, nr 4, s. 490-497Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pressurized ventilation acts to increase the oxygen supply to roots and rhizomes in some species of emergent plants. In a greenhouse experiment, we investigated how pressurized ventilation affected growth, biomass allocation and mineral content of Phragmites australis in two water depths (15 cm or 75 cm) and two substrates (organic sediment or sand). Through perforating each stem above the water surface, pressurized ventilation was inhibited without affecting oxygen diffusion. In controls, 10-20% of the stems were perforated to make certain that lack of efflux sites would not limit pressurized ventilation. Plants with inhibited pressurized ventilation had lower oxygen concentrations in their stem bases than control plants. Growth was lower in plants with inhibited pressurized ventilation compared to controls except when plants grew in a combination of sand and shallow water. In plants grown in an organic sediment, but not in those grown in sand, inhibition of pressurized ventilation resulted in decreased biomass allocation to soil roots but increased allocation to aquatic roots. Stem perforation affected the tissue concentrations of nitrogen, phosphorus, magnesium, manganese and aluminium but not of calcium or iron. We suggest that the lower growth in plants with inhibited pressurized ventilation was caused by decreased mineral uptake, which may have resulted from the decreased proportional allocation to soil root weight, from decreased mineral availability or from impaired root function. In plants grown in sand in shallow water, diffusion seemed to cover the oxygen demand, as pressurized ventilation did not affect growth.

  • 40.
    Waara, Sylvia
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Dagvattnets sammansättning i Västerås stad - En kunskapssammanställning2010Rapport (Annet vitenskapelig)
  • 41.
    Waara, Sylvia
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Gajewska, Magdalena
    Gdańsk University of Technology, Gdańsk, Poland.
    Dvarioniene, Jolanta
    Kaunas University of Technology, Kaunas, Lithuania.
    Ehde, Per Magnus
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Gajewski, Ryszard
    Gdańska Infrastructura Wodociągowo-Kanalizacyjna, Gdańsk, Poland.
    Grabowski, Pawel
    Grupa Lotos, Gdańsk, Poland.
    Hansson, Anna
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Kaszubowski, Jacek
    Gdańska Infrastructura Wodociągowo-Kanalizacyjna, Gdańsk, Poland.
    Obarska-Pempkowiak, Hanna
    Gdańsk University of Technology, Gdańsk, Poland.
    Przewlócka, Maria
    Gdańsk University of Technology, Gdańsk, Poland.
    Pilecki, Adam
    Grupa Lotos, Gdańsk, Poland.
    Nagórka-Kmiecik, Dagmara
    City Hall of Gdańsk, Environment Department , Gdańsk, Poland.
    Skarbek, Jacek
    Gdańska Infrastructura Wodociągowo-Kanalizacyjna, Gdańsk, Poland.
    Tonderski, Karin
    Linköping University, Linköping, Sweden.
    Weisner, Stefan
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Wojciechowska, Ewa
    Gdańsk University of Technology, Gdańsk, Poland.
    Towards Recommendations for Design of Wetlands for Post-Tertiary Treatment of Waste Water in the Baltic Sea Region – Gdańsk Case Study2014Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    There are many challenges that need to be addressed if the far reaching objectives on high environmental status as required in the EU Water Framework Directive and the Marine Strategy Framework Directive will be met in the Baltic Sea Region within the next decade. For wastewater treatment plants (WWTP) this implies, in spite of the many improvements made during the last decade, development and introduction of new technology to further reduce eutrophying compounds, hazardous chemicals and pharmaceuticals. Constructed wetlands when properly designed and operated have been shown to be robust systems with low energy requirements that may not only reduce many types of pollutants but may also provide many additional ecosystem services beyond requirements generally imposed by authorities. For example, they may support and enhance biodiversity and be used to convert brownfield areas in urban landscapes to recreational areas. Reduced cost is possible if treated water is reused in industry or for irrigation. In a project, supported by the Swedish Institute, a group of scientists, a water company and water using industry has together with local authorities through workshops, field studies and literature studies worked on finding a general first recommendation on design and operation. In this paper we will present the scientific rational and legal constraints for the general design and operation of a wetland system for post-tertiary treatment of waste water from WWTPs using Gdańsk as an example. The proposal includes a first part, which mainly will be focusing on pollutant and pathogen removal using particle traps and a HSSF wetland on land owned by the WWTP and a second part consisting of a FWS wetland which, in addition to further polishing the water, will enhance biodiversity and provide recreational areas on derelict land owned by the city.

  • 42.
    Waara, Sylvia
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Khokhotva, Oleksandr
    National Technical University of Ukraine, Kyiv Polytechnic Institute, Kyiv, Ukraine.
    The effect of environmental conditions on the stability of heavy meltal-filter material complex as assessed by the leaching of adsorbed metal ions2011Inngår i: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 159, s. 146-1463Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study the influence of environmental conditions, most likely prevailing in filter beds used for intermittently discharged pollutant streams such as landfill leachate and storm water, on the stability of the heavy metalefilter complex was investigated for 2 filter materials; non-treated and urea treated pine bark, using leaching experiments. The metalefilter complex stability was higher for urea treated than for non-treated pine bark and dependent on the metal adsorbed. The type of environmental condition applied was of less importance for the extent of leaching.

  • 43.
    Waara, Sylvia
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Wojciechowska, Eva
    Faculty of Civil & Environmental Engineering, Gdansk University of Technology, Gdansk, Polen.
    Distribution and removal efficiency of heavy metals in two constructed wetlands treating landfill leachate2011Inngår i: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 64, nr 8, s. 1597-1606Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The results of heavy metals (Fe, Mn, Zn, Ni, Cu, Cr, Pb, Cd) removal and partitioning between aqueous and solid phases at two treatment wetlands (TWs) treating municipal landfill leachates are presented. One of the TWs is a surface flow facility consisting of 10 ponds. The other TW is a newly constructed pilot-scale facility consisting of three beds with alternately vertical and horizontal sub-surface flow. The metals concentrations were analysed in leachate (both TWs) and bottom sediments (surface flow TW). Very high (90.9-99.9%) removal rates of metals were observed in a mature surface flow TW. The effectiveness of metals removal in a newly constructed pilot-scale sub-surface flow wetland were considerably lower (range 0-73%). This is attributed to young age of the TW, different hydraulic conditions (sub-surface flow system with much shorter retention time, unoxic conditions) and presence of metallic complexes with refractory organic matter

  • 44.
    Weisner, Stefan
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Potential hos våtmarker anlagda för fosfor- och kväveretention i jordbrukslandskapet: analys och tolkning av mätresultat2012Rapport (Annet vitenskapelig)
  • 45.
    Weisner, Stefan
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Problems in determining the amounts of nutrients removed in wetlands created to abate run-off from agricultural fields without using excessively costly measurements2012Inngår i: Proceedings from the 7th SWS 2012 European chapter meeting: Wetland restoration – challenges and opportunities : Programme and abstracts, 17-21 June 2012 / [ed] Brian Kronvang, Carl Christian Hoffmann & Mirela Lăcrămioara Vlad, Aarhus: Aarhus University, DCE - Danish Centre for Environment and Energy , 2012, s. 53-53Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Creation of wetlands in the agricultural landscape has in Sweden been identified as a cost-effective way of decreasing nutrient transports to the Baltic Sea. Approximately 3,000 wetlands have been constructed so far in southern Sweden through different subsidy systems. The purpose is that these wetlands should counteract eutrophication by removing nitrogen and phosphorus while simultaneously contributing to increased biodiversity in the landscape.

    Continuous automatic (flow or time proportional) water sampling for nitrogen and phosphorus removal measurements were carried out in the inlet and outlet of 7 wetlands during 1.5 to 10 years. Strategic grab sampling, also in the inlet and outlet, was conducted in 14 wetlands during 2 years. Flow was measured only in the outlet in most wetlands. The wetlands were all located in agricultural areas and were chosen to represent wetlands with different nutrient loads from agricultural field run-off.

    Large temporal variations in water flows and concentrations complicated the interpretation of data. Analyses of the large dataset, in some cases comprising parallel measurements using different methods, showed that estimations of nutrients removal were, for example, sensitive to if short intensive inflows were adequately captured with the measurements or not. This led in particular to substantial underestimations of phosphorus removal.

    This suggests that removal rates or coefficients used in models to estimate the total amounts of nutrients removed from agricultural run-off in large-scale national programs for creating wetlands may be based on field measurements with severe shortcomings. National assessments may therefore have given misleading results and, at least for phosphorus, seriously underestimated the amount of removal that has been obtained. We need to find ways to accurately determine nutrient removal levels of a large amount of wetlands without using too costly measurements so that created wetlands retain their status as a cost-effective way to reduce nutrient transports from agriculture.

  • 46.
    Weisner, Stefan
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Vilka faktorer styr kväveretentionen ianlagda våtmarker?: Resultat från experimentvåtmarker vid Plönninge2008Rapport (Annet vitenskapelig)
  • 47.
    Weisner, Stefan
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Våtmarker i jordbrukslandskapet som åtgärd mot övergödning: kväveretention och  kostnadseffektivitet2008Rapport (Annet vitenskapelig)
  • 48.
    Weisner, Stefan E. B.
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Strand, John A.
    Rural economy and agricultural society, Lilla Böslid, Eldsberga.
    Ecology and management of plants in aquatic ecosystems2002Inngår i: Handbook of ecological restoration: Vol. 1, Principles of restoration / [ed] Martin R. Perrow, Anthony J. Davy, Cambridge: Cambridge University Press , 2002, s. 242-256Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    The central role of macrophytes for the functioning of aquatic systems means that the most effective way to manage these systems is often through vegetation management. For this we need to understand the mechanisms regulating vegetation distribution. Submerged macrophyte distribution is mainly related to water depth, water transparency and epiphytic growth. The distribution of emergent vegetation can largely be predicted from water depth and substrate characteristics. Also, in both submerged and emergent macrophytes, the effects on the vegetation of grazing can be dramatic. Management should aim at providing environmental conditions favouring the desired ecosystem state, rather than methods directly aimed at the vegetation. For example, the best method for promoting establishment of emergent vegetation is often lowering of the water level. To establish submerged vegetation, water transparency can be increased through biomanipulation (the removal of zooplanktivorous fish leading to increased zooplankton grazing pressure on phytoplankton). Changes in water depth and introduction of grazers are often effective measures to control growth of aquatic weeds.

  • 49.
    Weisner, Stefan E.B
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Bastviken Kallner, Sofia
    Department of Biology, Linköping University.
    Thiere, Geraldine
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Ehde, Per Magnus
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Tonderski, Karin S.
    Department of Biology, Linköping University.
    Influence of alternative states on nitrogen removal in experimental wetlands2007Inngår i: 2nd International Symposium on Wetland Pollutant Dynamics and Control - WETPOL 2007: extended abstracts / [ed] Mander Ülo, Koiv Margi, Vohla Chrisitna, Tartu: Institute of Geography, University of Tartu , 2007, s. 357-359Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Denitrification is the main process that remove nitrate from the water in wetlands. Plants can supply denitrifying bacteria with organic carbon and suitable attachment surfaces (Weisner et al. 1994). They also promote the development of anaerobic conditions through litter accumulation and decomposition, which would favour denitrification. The presence of plants has been shown to enhance nitrate removal in field studies (Bachand and Horne 2000). Toet et al. (2005) found a higher nitrogen removal in wetland compartments with emergent plants than with submersed plants. Results from microcosm studies have shown that the potential for denitrification is specific for different plant species (Bastviken et al. 2005).

    Wetlands may typically exist in alternative states, dominated by different kinds of vegetation. The purpose of this study was to investigate the effect of alternative state on nitrogen removal under controlled conditions in experimental wetlands.

  • 50.
    Weisner, Stefan E.B.
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Miao, Shi Li
    Everglades Department, South Florida Water Management District, West Palm Beach, USA .
    Use of morphological variability in Cladium jamaicense and Typha domingensis to understand vegetation changes in an Everglades marsh2004Inngår i: Aquatic Botany, ISSN 0304-3770, E-ISSN 1879-1522, Vol. 78, nr 4, s. 319-335Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The northern Florida Everglades have experienced an expansion of cattail (Typha domingensis) and a decrease of sawgrass (Cladium jamaicense) communities. In this study, spatial and temporal within-species variability in plant performance were used to explore the mechanisms causing the distributional changes of cattail and sawgrass. Biomass, shoot density, plant weight, shoot height, and biomass allocation to different plant components (leaves, shoot bases, roots and rhizomes), were sampled in cattail and sawgrass stands along a nutrient gradient within water conservation area 2A during two sequential years with different water level conditions. The shoot height–leaf weight relationships were analysed with allometric methods. Sawgrass exhibited responses to nutrient limitation that resembled functional responses to deep water, indicating that impact of deep water was stronger when plant growth was limited by nutrient deficiency. In cattail, responses along the nutrient gradient were less pronounced. Plant responses along the nutrient gradient differed between years. This was most evident in sawgrass, showing that this species was more affected by water depth than cattail. Responses in sawgrass suggested that this species had to sacrifice important plant functions in deep water at low-nutrient sites. The results in this study emphasise that, to preserve and restore sawgrass communities, lower water levels are required. For cattail, a combination of low phosphorus availability and disturbances (such as extended droughts and outbreaks of herbivores) is needed to stop the ongoing expansion. Management of these ecosystems must consider the relative roles of water level, nutrient enrichment, and disturbances, for vegetation development.

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