ORIGINAL ARTICLE Quantifying nutrient removal from groundwater seepage out of constructed wetlands receiving treated wastewater effluent Jessica R. Ackerman • Eric W. Peterson • Stephen Van der Hoven • William L. Perry Received: 14 August 2014 / Accepted: 8 February 2015 Ó Springer-Verlag Berlin Heidelberg 2015 Abstract Wetlands play an important role in the reduc- tion of nutrients in agricultural runoff and treated waste- water effluent. A component of wetlands systems, the seepage out of the wetland and subsequent groundwater flow, has been virtually ignored in understanding the transport and fate of nutrients. This study examined the flow of groundwater infiltrating from a constructed wetland receiving municipal wastewater effluent, and the fate of dissolved nutrients within the groundwater. Concentrations of nitrate, ammonium, phosphate and chloride were used to assess the quantity of nutrients being removed/added from the seepage compared to the total amount removed/added by surface water processes. Nitrate–Nitrogen concentra- tions in the surface water ranged 10.0–26.8 and ND- 1.5 mg/L in groundwater. Ammonium–Nitrogen concen- trations in the surface water ranged 0.05–2.3 and 0.004–4.5 mg/L in groundwater. Phosphate concentrations in the surface water ranged 0.1–3.2 and ND-0.4 mg/L in groundwater. Effluent-groundwater mixing calculations showed that a majority of the water sampled from the wells is effluent rich (50–100 %). MODFLOW simulations suggest that groundwater seepage flux from the wetland was between 3 and 11 % of the surface water flux through the wetland. Nitrate and phosphate removal was deter- mined to be significant in the groundwater—1930 and 175 g/day, respectively, but ammonium concentrations increased in the groundwater by 29 g/day. Dependent on surface water retention times in the wetland, nitrate re- moval from the surface water ranged from 4100 to 14,450 g/day. Ammonium and phosphate were added at rates between 21–74 and 221–780 g/day, respectively. Keywords Wetlands  Nitrate  Ammonium  Phosphate  Groundwater  Model Introduction Wetlands are recognized as a natural solution for many different water quality issues. Wetlands provide water storage and flood protection during wet periods, serve as water reserves during dry periods, retain sediments, remove nutrients and pollutants through adsorption, uptake, and microbial processes, and provide habitat for aquatic birds and other species with aquatic life stages (Hattermann et al. 2008). Constructed wetlands are being employed to miti- gate impacts to surface water as a result of point and non- point sources by removing or withholding a portion of pollutants via plant uptake and biogeochemical processes (Haberl et al. 2003; Mitsch et al. 2001). In agricultural settings, constructed wetlands have been installed to intercept nutrient-rich tile water prior to being discharged into a stream or larger body of water. Con- structed wetlands decrease the nutrient concentrations through vegetation and algal uptake (Drever 1997; Jin et al. 2002), adsorption (Chavan et al. 2008; Jin et al. 2002), J. R. Ackerman  E. W. Peterson (&)  S. Van der Hoven Department of Geography-Geology, Illinois State University, Campus Box 4400, Normal, IL 61790, USA e-mail: ewpeter@ilstu.edu J. R. Ackerman Illinois State Geological Survey, Champaign, IL 61820, USA S. Van der Hoven Genesis Engineering & Redevelopment, Inc., Ripon, CA 95366, USA W. L. Perry School of Biological Sciences, Illinois State University, Normal, IL 61790, USA 123 Environ Earth Sci DOI 10.1007/s12665-015-4167-3