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A field-scale approach to estimate nitrate loading to groundwater

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doi: 10.2134/jeq2017.09.0369
Authors:Malekani, Farzin; Ryan, M. Cathryn; Zebarth, Bernie J.; Loo, Shawn E.; Suchy, Martin; Cey, Edwin E.
Author Affiliations:Primary:
University of Calgary, Department of Geoscience, Calgary, AB, Canada
Other:
Agriculture and Agri-Food Canada, Canada
Environment and Climate Change Canada, Canada
Volume Title:Journal of Environmental Quality
Source:and [Journal of Environmental Quality, 47(4), p.795-804. Publisher: American Society of Agronomy,] Crop Science Society of America, Soil Science Society of America, Madison, WI, United States. ISSN: 0047-2425
Publication Date:2018
Note:In English. 55 refs.; illus., incl. sketch map
Summary:The quantification of groundwater NO3 loading associated with a specific field or set of management practices so that groundwater quality improvements can be objectively assessed is a major challenge. The magnitude and timing of NO3 export from a single agricultural field under raspberry (Rubus idaeus L.) production were investigated by combining high-resolution groundwater NO3 concentration profiles (sampled using passive diffusion samplers) with Darcy's flux estimation at the field's down-gradient edge (based on field-measured hydraulic gradients and laboratory-estimated hydraulic conductivity). Annual recharge estimated using Darcy's law (1002 mm) was similar to that obtained using two other approaches. The similarity in the rate of Cl applied to the field and the estimated export flux over the 1-yr monitoring period (51 vs. 56 kg Cl ha-1) suggested the mass flux estimation approach was robust. An estimated 80 kg NO3-N ha-1 was exported from the agricultural field over the 1-yr monitoring period. The greatest monthly groundwater mass flux exported was observed in February and March (∼11 kg NO3-N ha-1), and was associated with NO3 leached from the soil zone during the onset of precipitation in the previous autumn. Provided the groundwater recharged from the field of interest can be isolated within a vertical profile, this approach is an effective method for obtaining spatially integrated estimates of the magnitude and timing of NO3- loading to groundwater.
Subjects:Aquifer vulnerability; Aquifers; Chemical properties; Chloride ion; Chlorine; Concentration; Critical load; Darcy's law; Diffusivity; Evapotranspiration; Fluctuations; Ground water; Halogens; High-resolution methods; Hydraulic conductivity; Hydrology; Leaching; Lysimeters; Nitrate ion; Nitrification; Observation wells; Rainfall; Recharge; Seasonal variations; Soil quality; Soils; Tracers; Water management; Water quality; Water table; United States; Washington; Whatcom County Washington; Abbotsford-Sumas Aquifer
Coordinates:N483700 N490000 W1204000 W1230300
Record ID:842215-5
Copyright Information:GeoRef, Copyright 2021 American Geosciences Institute.
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