Subsurface transport of orthophosphate in five agricultural watersheds, USA
Journal of Hydrology
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Abstract
Concentrations 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.
Suggested Citation
Domagalski, J.L., and Johnson, H.M., 2011, Subsurface transport of orthophosphate in five agricultural watersheds, USA: Journal of Hydrology, v. 409, no. 1-2, p. 157-171, https://doi.org/10.1016/j.jhydrol.2011.08.014.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Subsurface transport of orthophosphate in five agricultural watersheds, USA |
| Series title | Journal of Hydrology |
| DOI | 10.1016/j.jhydrol.2011.08.014 |
| Volume | 409 |
| Issue | 1-2 |
| Year Published | 2011 |
| Language | English |
| Publisher | Elsevier |
| Publisher location | Amsterdam, Netherlands |
| Contributing office(s) | California Water Science Center, Oregon Water Science Center |
| Description | 15 p. |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Journal of Hydrology |
| First page | 157 |
| Last page | 171 |