March 21, 2014
Water researchers follow the trail of Alberta鈥檚 agricultural runoff
Bernhard Mayer tracks sources of nitrate in ground water and surface water in agricultural areas.
Every year, up to 65 per cent of the water consumed in Alberta is used in irrigation to grow a wide variety of crops and Bernhard Mayer is one of the researchers examining that water once it ends up back in the province鈥檚 rivers and aquifers.
The professor in the Department of Geoscience in the Faculty of Science, and research member of , tracks nitrogen in agricultural systems to see how much of it leaks either into ground water or surface water in areas that have agricultural land use.
鈥淚nternationally, nitrate is one of the most pervasive ground water pollutants because of intensive agriculture,鈥 says Mayer. 鈥淣itrate could be derived from synthetic fertilizers or from manure applications.鈥
He and his Applied Geochemistry research group use chemical and isotopic techniques to trace contaminants in surface and subsurface environments. He says southern Alberta is an excellent location to track agricultural pollutants in rivers because source waters from the mountains upstream hardly contain any nitrate.
鈥淣itrate contamination is much more severe in other places in the world,鈥 he says. 鈥淏ut in other countries it鈥檚 often more difficult to come up with conclusive statements because there are so many sources of nitrate and nitrogen that鈥檚 been applied to agricultural landscapes for decades.鈥
Graduate student June Chao, who works with Bernhard Mayer鈥檚 research group, sampling the Bow river.
Monitoring our drinking water
In the Bow River below 不良研究所, Mayer鈥檚 group found the majority of nitrate in the water comes from urban waste water treatment plants and 鈥渙nly a relatively small proportion鈥 from agriculture. 鈥淣one of that is above drinking water limits so there鈥檚 no real worry in terms of drinking water quality,鈥 he says.
In a study in the Oldman River basin in southern Alberta, where there are lots of feedlots, Mayer and his team found nitrate contamination in a non-drinking water aquifer and in tributaries to the Oldman River was derived from manure. 鈥淚f feedlot operators spread manure on the fields in excessive amounts, it鈥檚 possible that some of this nitrate ends up in the ground water,鈥 he says.
The amount of nitrogen allowed in drinking water is regulated 鈥 the maximum allowable concentration is 10 milligrams nitrate-N per litre 鈥 and given that Alberta鈥檚 agriculture industry is the largest user of water in the province, it鈥檚 important to monitor its effects.
鈥淲hen it comes to nitrate pollution of surface water,鈥 he says, 鈥渋t鈥檚 always good to have a handle on which percentage of the pollution comes from which source.鈥