WATER QUALITY AND NUTRIENT RETENTION IN A NEWLY CONSTRUCTED ALKALINE FEN WETLAND IN LANCASTER COUNTY, PENNSYLVANIA

We examined the nutrient retention potential of a small (<1 ha) constructed wetland in West Lampeter Township, Lancaster County, PA. The wetland receives surface water inflow from a 1.5 km² watershed dominated agricultural land use. The wetland is populated with a wetland plant community primarily composed of Carex stricta, Peltandra virginica, Scirpus validus and Typha latifolia. We collected bi-weekly grab samples of surface water flowing into, within and out of the wetland following wetland construction and establishment of the plant community. Over the duration of the sample period, we documented a modification in surface water quality as surface water passed through the wetland. In particular, water pH at the inflow averaged 8.1, increased to 8.9 within the wetland and averaged pH 9.2 at the outflow. Nitrate concentrations at the inflow averaged 5.6 mg/L NO₃-N, but declined to 2.6 mg/L NO₃-N within the wetland and declined again to a value of 2.0 mg/L NO₃-N at the outfall. The concentration of soluble reactive phosphate in water flowing through the wetland did not vary significantly and averaged 0.19 mg/L PO₄^-3 in wetland inflow, 0.23 mg/L PO₄^-3 within the wetland and 0.20 mg/L PO₄^-3 in the outflow. These data suggest that for the duration of our sampling period the wetland acted as a net sink for nitrate.