Changes

In addition to contaminating surface waters, abundance of nutrients can also contaminate the ground waters. Contrary to surface waters, nitrogen is the primary nutrient of concern  regarding groundwater quality. Hobbie, et al. (2017<ref name="example2">Hobbie, S.E., Finlay, J.C., Janke, B.D., Nidzgorski, D.A., Millet, D.B., Baker, L.A., 2017. Contrasting nitrogen and phosphorus budgets in urban watersheds and implications for managing urban water pollution. Proc. Natl. Acad. Sci. U. S. A. 114 (16), 4177–4182.</ref>) reported that only 22 % of phosphorous is retained within its watershed, while the same estimated for nitrogen is 80%. Therefore, most of the nitrogen is leached in the groundwater or transformed through denitrification. Phosphorus retained in the watershed is often in particle form. Therefore, it tends to be bound to soil particles and retained in the vadose zone (area between ground surface and the groundwater table). However, nitrogen is often available in dissolved form which is more mobile and bioavailable. Thus, it can travel through the vadose zone and contaminate the groundwater.

In addition to contaminating surface waters, abundance of nutrients can also contaminate the ground waters. Contrary to surface waters, nitrogen is the primary nutrient of concern  regarding groundwater quality. Hobbie, et al. (2017<ref name="example2">Hobbie, S.E., Finlay, J.C., Janke, B.D., Nidzgorski, D.A., Millet, D.B., Baker, L.A., 2017. Contrasting nitrogen and phosphorus budgets in urban watersheds and implications for managing urban water pollution. Proc. Natl. Acad. Sci. U. S. A. 114 (16), 4177–4182.</ref>) reported that only 22 % of phosphorous is retained within its watershed, while the same estimated for nitrogen is 80%. Therefore, most of the nitrogen is leached in the groundwater or transformed through denitrification. Phosphorus retained in the watershed is often in particle form. Therefore, it tends to be bound to soil particles and retained in the vadose zone (area between ground surface and the groundwater table). However, nitrogen is often available in dissolved form which is more mobile and bioavailable. Thus, it can travel through the vadose zone and contaminate the groundwater.

==Nutrient Management==

==Nutrient management==

Due to their differing stoichiometry, managing nitrogen pollution is different from that of phosphorous. To reduce the nitrogen pollution, the watershed inputs should be reduced in general, while reducing phosphorus pollution would require reducing the movement of phosphorus from the contributing areas in the watershed (Hobbie et al., 2017<ref name="example2" />).

Due to their differing stoichiometry, managing nitrogen pollution is different from that of phosphorous. To reduce the nitrogen pollution, the watershed inputs should be reduced in general, while reducing phosphorus pollution would require reducing the movement of phosphorus from the contributing areas in the watershed (Hobbie et al., 2017<ref name="example2" />).