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Phosphorus Retention in a Newly Constructed Wetland Receiving Agricultural Tile Drainage Water
Author(s) -
Kynkäänniemi Pia,
Ulén Barbro,
Torstensson Gunnar,
Tonderski Karin S.
Publication year - 2013
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2012.0266
Subject(s) - hydrology (agriculture) , wetland , environmental science , snowmelt , tile drainage , eutrophication , soil water , drainage , phosphorus , drainage basin , surface water , sink (geography) , subsurface flow , water quality , surface runoff , nutrient , environmental engineering , groundwater , ecology , soil science , chemistry , geology , geotechnical engineering , cartography , organic chemistry , geography , biology
One measure used in Sweden to mitigate eutrophication of waters is the construction of small wetlands (free water surface wetland for phosphorus retention [P wetlands]) to trap particulate phosphorus (PP) transported in ditches and streams. This study evaluated P retention dynamics in a newly constructed P wetland serving a 26‐ha agricultural catchment with clay soil. Flow‐proportional composite water samples were collected at the wetland inlet and outlet over 2 yr (2010–2011) and analyzed for total P (TP), dissolved P (DP), particulate P (PP), and total suspended solids (TSS). Both winters had unusually long periods of snow accumulation, and additional time‐proportional water samples were frequently collected during snowmelt. Inflow TP and DP concentrations varied greatly (0.02–1.09 mg L −1 ) during the sampling period. During snowmelt in 2010, there was a daily oscillation in P concentration and water flow in line with air temperature variations. Outflow P concentrations were generally lower than inflow concentrations, with net P losses observed only in August and December 2010. On an annual basis, the wetland acted as a net P sink, with mean specific retention of 69 kg TP, 17 kg DP, and 30 t TSS ha −1 yr −1 , corresponding to a reduction in losses of 0.22 kg TP ha −1 yr −1 from the agricultural catchment. Relative retention was high (36% TP, 9% DP, and 36% TSS), indicating that small constructed wetlands (0.3% of catchment area) can substantially reduce P loads from agricultural clay soils with moderately undulating topography.