Sources and fate of nitrate in groundwater at agricultural operations overlying glacial sediments

摘要: Leaching of nitrate (NO3-) from animal waste or fertilisers at agricultural operations can result in NO3- contamination of groundwater, lakes, and streams. Understanding the sources fate of nitrate groundwater systems glacial sediments, which underlie many agricultural operations, is critical for managing impacts human food production on environment. Elevated concentrations in groundwater be naturally attenuated through mixing denitrification. Here we use isotopic enrichment stable isotope values of NO3- to quantify amount denitrification at two confined feeding overlying sediments Alberta, Canada. Uncertainty δ15NNO3 and δ18ONO3 source and denitrification factors are accounted using a Monte Carlo approach. When could quantified, used these to constrain model based Cl− concentrations. Using this novel approach were able reconstruct the initial NO3−N concentration NO3-N/Cl- ratio at the point entry system. Manure filtrate had total nitrogen (TN) up 1820 mg L−1, was predominantly organic N NH3. Groundwater had 85 mg L−1 TN, which was predominantly NO3-. The addition the local system temporary manure piles pens equalled or exceeded additions earthen storages these sites. On-farm management should therefore increasingly focus on limiting direct contact with soil encourage storage lined lagoons. Nitrate attenuation both sites attributed to a spatially variable combination denitrification, but is dominated by denitrification. Where identified, reduced agriculturally derived least half and, in some wells, completely. Infiltration glacial sediments where likely preferable off-farm export via runoff drainage networks, especially if local not potable water supply.