Nitrogen and phosphorus removal from agricultural runoff in integrated buffer zones

Transcription

1 supporting information Nitrogen and phosphorus removal from agricultural runoff in integrated buffer zones Dominik Zak 1, 2*, Brian Kronvang 1, Mette V. Carstensen 1, Carl C. Hoffmann 1, Ane Kjeldgaard 1, Søren E. Larsen 1, Joachim Audet 1, 3, Sara Egemose 4, Charlotte A. Jorgensen 4, Peter Feuerbach 5, Flemming Gertz 6, Henning S. Jensen 4 1 Department of Bioscience, Aarhus University, Vejlsøvej 25, 8600 Silkeborg, Denmark 2 Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 301, Berlin, Germany 3 Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, P.O. Box 7050, SE Uppsala, Sweden. 4 Department of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark 5 Department of Wetlands & Biodiversity, Hushållningssällskapet Halland, SE Eldsberga, Sweden 6 SEGES, Agro Food Park 15, DK-8200 Aarhus N, Denmark *Corresponding author, doz@bios.au.dk, phone: , fax: page S1

2 Figure S1. Hydrographs of a-b) the water discharge at the inlet and outlet and c-d) water levels in the ditch-like pond of the two neighboring integrated buffer zones (IBZ I and IBZ II, see Figure 1). The steep decrease in water levels in May 2015 (Upstream) and December 2015 (Downstream) was due to the emptying of the basins for a hydrological experiment. page S2

3 Figure S2. Normalized breakthrough curves (c t /c 0 ) of the four piezometer (PIEZO) transects in the filter bed (FILTERBED) of the integrated buffer zone (IBZ I, Fig. 1). There were six PIEZOs in one transect three shallow (s) PIEZOs placed at up to 0.3 m depth and three PIEZOs in the deeper (d) soil placed at up to 1.1 m depth of the FILTERBED. The left row represents the PIEZOs located close to the POND and the right row represents PIEZOs at the end of the FILTERBED. Thus, the water flow direction is from left to right. As illustrated, not all parts of the FILTERBED were percolated during the experiment, HRT accounting for approx. 6 days. page S3

4 Figure S3. Normalized breakthrough curves (c t /c 0 ) of the four piezometer (PIEZO) transects in the filter bed (FILTERBED) of the integrated buffer zone (IBZ II, Figure 1). There were six PIEZOs in one transect three shallow (s) PIEZOs placed at up to 0.3 m depth and three PIEZOs in the deeper (d) soil placed at up to 1.1 m depth of the FILTERBED. The left row represents the PIEZOs located close to the POND and the right row represents PIEZOs at the end of the FILTERBED. Thus, most parts of the FILTERBED were percolated during the experiment, HRT accounting for approx. 3 days. Some PIEZOS were out of order, probably due to clogging of the slits. page S4

5 Figure S4. Relationships between monthly cumulated absolute load and removal (kg) for nitrate, total nitrogen (TN), soluble reactive phosphorus (SRP) and total P (TP) of the two integrated buffer zones (IBZ I and II, Figure 1). page S5

6 Figure S5. Relationships between monthly averaged loading rate (g N m -2 d -1, mg P m -2 d -1 ) and removal efficiency (%) for nitrate and soluble reactive phosphorus (SRP) for, respectively, the ditchlike pond (POND) and the filter bed (FILTER) of the two integrated buffer zones (IBZ I and II, Figure 1). page S6

7 Figure S6. Relationships between the monthly average hydraulic residence time and the removal efficiency for nitrate, total nitrogen (TN), soluble reactive phosphorus (SRP) and total P (TP) of the ditch-like pond of the two integrated buffer zones (IBZ I and II, Figure 1). page S7

8 Figure S7. Manual for integrated buffer zones as edge of field technology for mitigation of nutrient pollution (photo credit: SEGES). page S8

9 Table S1: Overview of the concentrations in the water inlet and outlet of the pond-like ditch (POND) and in the piezometers (Outlet FILTERBED) as well as the daily loads of the POND and of the FILTERBED of nitrate-n (NO - 3 -N), ammonium-n (NH + 4 -N) total nitrogen (TN), soluble reactive phosphorus (SRP), and total phosphorus (TP) for the integrated buffer zones (IBZ I, IBZ II, see Fig. 1). To calculate the loading rates for the FILTERBED, POND concentrations were used. For the Outlet FILTERBED concentration, data from the piezometer at the end of the FILTERBED were used (Fig. 1) Values represent mean (Ave), minimum (Min) and maximum (Max) values of the monitoring period from March 2015 to July Nitrite was omitted because concentrations were lower than the detection limit (0.005 mg N L -1 ) during the major part of the monitoring period. Inlet POND POND Outlet POND Outlet FILTERBED POND FILTERBED IBZ I, II IBZ I IBZ II IBZ I IBZ II IBZ I IBZ II IBZ I IBZ II IBZ I IBZ II concentration (mg N L -1, µg P L -1 ) load (g N m -2 ; mg P m -2 ) NO - 3 -N Ave Min Max NH + 4 -N Ave Min Max TN/DIN* Ave Min Max SRP Ave Min Max TP/TDP* Ave Min Max *For FILTERBED DIN (dissolved inorganic nitrogen) and TDP (total dissolved phosphorus), values are given assuming that particle transport is negligible/are based on the assumption of negligible particle transport. page S9

10 Table S2: Removal of nutrients (g N m -2 month -1, mg P m -2 month -1 ) in the ditch-like pond (POND), in the filter bed (FILTERBED) and in total (TOT) for the integrated buffer zones (IBZ I and IBZ II, see Fig. 1). Values represent mean (Ave), minimum (Min) and maximum (Max) values in the monitoring period from March 2015 to July IBZ I IBZ II POND FILTERBED TOT POND FILTERBED TOT Nitrate Ave Min Max Total nitrogen Ave Min Max Soluble reactive phosphorus Ave Min Max Total phosphorus Ave Min Max page S10