Spatial and temporal variation of nitrate contamination was assessed in a study area within the Canadian portion of the Abbotsford/Sumas Aquifer that covers an area of 100 km2.
Elevated nitrate concentrations were observed over a wide portion of the aquifer.
Only minor decreases in nitrate concentrations were measured with depths up to 20 m below the water table.
The results are consistent with a wide-spread, non-point source of contamination.
The spatial distribution of high nitrate concentrations appeared to correlate with agricultural land use patterns.
A nitrogen budget calculation was performed based on nitrogen additions and losses to the root zone of the agricultural land in a study area located over the aquifer. using 1971,1981 and 1991 census data.
Nitrogen additions exceeded N removals by 134,185, and 245 kg N ha - 1 in 1971,1981, and 1991. respectively, indicating a high potential for nitrate leaching to occur.
The increase in the nitrogen surplus was primarily the result of changes in land use.
In particular, the agricultural land base decreased by almost 20%, and there was a shift from animal production systems which require a local land base for crop production and grazing to animal production where the feed is imported.
The N balance calculations were internally consistent with N budgets constructed for individual agricultural operations over the aquifer. (...)
Mots-clés Pascal : Occupation sol, Agriculture, Contamination, Pollution sol, Lessivage, Qualité eau, Gestion déchet, Fumier ferme, Elevage, Nitrate, Colombie britannique, Canada, Amérique du Nord, Amérique, Nappe eau, Technique culturale, Hydrogéologie
Mots-clés Pascal anglais : Land use, Agriculture, Contamination, Soil pollution, Leaching, Water quality, Waste management, Farmyard manure, Rearing, Nitrates, British Columbia, Canada, North America, America, Aquifers, Cultural practice, Hydrogeology
Notice produite par :
Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 98-0349168
Code Inist : 001D16B04. Création : 27/11/1998.