| The extreme amounts of nutrients are both due to the general increase of their availability and the decreased removal capacity of natural systems. Following the important technological advancements in early 20th century (Haber-Bosch process), nitrogen in the form of ammonia has increased significantly due to the ongoing production of fertilizers. While the increase in agricultural production has been a beneficial effect of this finding, it has also led to excessive amounts of nutrient source loading. The decrease in nutrient retention capacity is due to the modification of natural systems such as the increased impervious surfaces along with reduction of [[vegetation]], stream channelization and modification and degradation of riparian zones (Collins et al, 2010<ref>Collins, K.A., Lawrence, T.J., Stander, E.K., Jontos, R.J., Kaushal, S.S., Newcomer, T.A., Grimm, N.B. and Ekberg, M.L.C., 2010. Opportunities and challenges for managing nitrogen in urban stormwater: A review and synthesis. Ecological Engineering, 36(11), pp.1507-1519.</ref>). | | The extreme amounts of nutrients are both due to the general increase of their availability and the decreased removal capacity of natural systems. Following the important technological advancements in early 20th century (Haber-Bosch process), nitrogen in the form of ammonia has increased significantly due to the ongoing production of fertilizers. While the increase in agricultural production has been a beneficial effect of this finding, it has also led to excessive amounts of nutrient source loading. The decrease in nutrient retention capacity is due to the modification of natural systems such as the increased impervious surfaces along with reduction of [[vegetation]], stream channelization and modification and degradation of riparian zones (Collins et al, 2010<ref>Collins, K.A., Lawrence, T.J., Stander, E.K., Jontos, R.J., Kaushal, S.S., Newcomer, T.A., Grimm, N.B. and Ekberg, M.L.C., 2010. Opportunities and challenges for managing nitrogen in urban stormwater: A review and synthesis. Ecological Engineering, 36(11), pp.1507-1519.</ref>). |