Groundwater flow path dynamics and nitrogen transport potential in the riparian zone of an agricultural headwater catchment

摘要: summary Shallow groundwater dynamics play a critical role in determining the chemistry and movement of nitrogen (N) riparian zone. In this study, we characterized N concentration variability hydrologic transport pathways shallow draining areas area with without emergent seeps. The study was conducted FD36, an agricultural headwater catchment Ridge Valley physiographic region central Pennsylvania, USA. Three seep adjacent non-seep were each instrumented field 40 piezometers installed grid pattern (1.5-m spacing) at both 20- 60-cm depths. Piezometers monitored seasonally for approximately two years (October 2010–May 2012). Results showed that hydraulic head within variable some regions exhibited upward vertical gradients 0.18–0.27. Non-seep by uniform levels relatively hydrostatic. Nitrate-N (NO3-N) concentrations significantly greater than those three sites. A two-component mixing model using chloride as conservative tracer indicated primarily (53–75%) comprised water from fractured aquifer, which had elevated NO3-N (5.7 mg L � 1 ). areas, however, (58–82%) perched on top fragipan likely recharged locally zone low (0.6 Higher concentrations, head, emergence onto land surface provided evidence preferential flow paths important conduit these We conclude potential delivery to stream FD36 much compared areas. Targeted management seeps should be priority efforts reduce zones catchments. Published Elsevier B.V.