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Johannesson, K., Tonderski, K., Wedding, B., Ehde, P. M. & Weisner, S. (2011). Phosphorus load variations and retention in non-point source wetlands in southern Sweden.
Open this publication in new window or tab >>Phosphorus load variations and retention in non-point source wetlands in southern Sweden
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2011 (English)Manuscript (preprint) (Other academic)
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.

National Category
Natural Sciences
Identifiers
urn:nbn:se:hh:diva-20141 (URN)978-91-7393-168-7 (ISBN)
Available from: 2012-12-14 Created: 2012-12-14 Last updated: 2018-03-22Bibliographically approved
Johannesson, K. M., Kynkäänniemi, P., Ulén, B., Weisner, S. E. .. & Tonderski, K. S. (2010). Clay-bound phosphorus retention in wetlands: a catchment comparison. In: 6th International Phosphorus Workshop (IPW6): Towards a sustainable control of diffuse P loss: risk, monitoring, modelling, and mitigation options : Book of Abstracts. Paper presented at 6th International Phosphorus Workshop (IPW6), Sevilla, Spain, 27 September - 1 October, 2010 (pp. 127-127).
Open this publication in new window or tab >>Clay-bound phosphorus retention in wetlands: a catchment comparison
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2010 (English)In: 6th International Phosphorus Workshop (IPW6): Towards a sustainable control of diffuse P loss: risk, monitoring, modelling, and mitigation options : Book of Abstracts, 2010, p. 127-127Conference paper, Published paper (Other academic)
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.

National Category
Natural Sciences
Identifiers
urn:nbn:se:hh:diva-14635 (URN)
Conference
6th International Phosphorus Workshop (IPW6), Sevilla, Spain, 27 September - 1 October, 2010
Available from: 2011-03-29 Created: 2011-03-24 Last updated: 2018-03-23Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-0722-6083

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