کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4577479 | 1630011 | 2011 | 15 صفحه PDF | دانلود رایگان |
SummaryConcentrations of dissolved orthophosphate (ortho P) in the unsaturated zone, groundwater, tile drains, and groundwater/stream water interfaces were assessed in five agricultural watersheds to determine the potential for subsurface transport. Concentrations of iron oxides were measured in the aquifer material and adsorption of ortho P on oxide surfaces was assessed by geochemical modeling. Attenuation of ortho P in these aquifers was attributed primarily to sorption onto iron oxides, and in one location onto clay minerals. Only one location showed a clear indication of phosphorus transport to a stream from groundwater discharge, although groundwater did contribute to the stream load elsewhere. Subsurface ortho P movement at a site in California resulted in a plume down gradient from orchards, which was attenuated by a 200 m thick riparian zone with natural vegetation. Iron oxides had an effect on phosphorus movement and concentrations at all locations, and groundwater chemistry, especially pH, exerted a major control on the amount of phosphorus adsorbed. Groundwater pH at a site in Maryland was below 5 and that resulted in complete sequestration of phosphorus and no movement toward the stream. Geochemical modeling indicated that as the surfaces approached saturation, groundwater concentrations of ortho P rise rapidly.
► Phosphorus transport in groundwater was assessed at five agricultural watersheds.
► Phosphorus subsurface movement was controlled by sorption onto iron oxides or clays.
► Water chemistry and soil types affected phosphorus transport to the aquifers.
► Low pH conditions within an aquifer in Maryland prevented phosphorus transport.
► Geochemical modeling was used to assess adsorption.
Journal: Journal of Hydrology - Volume 409, Issues 1–2, 28 October 2011, Pages 157–171