Changes

* '''Nitrification/denitrification''' – This is a microbial process where ammonia is converted to nitrite and then to nitrate by nitrifying bacteria. Through the denitrification process, the nitrate is further converted into gaseous nitrogen. This process is carried by denitrifying bacteria and requires anaerobic conditions. Anaerobic condition, can occur in lower depths of an LID, given the saturated conditions last long enough to minimize oxygen concentrations. Both processes require presence of organic matter as a source of energy.   

* '''Nitrification/denitrification''' – This is a microbial process where ammonia is converted to nitrite and then to nitrate by nitrifying bacteria. Through the denitrification process, the nitrate is further converted into gaseous nitrogen. This process is carried by denitrifying bacteria and requires anaerobic conditions. Anaerobic condition, can occur in lower depths of an LID, given the saturated conditions last long enough to minimize oxygen concentrations. Both processes require presence of organic matter as a source of energy.   

Each LID practice has the potential to offer one or all the mentioned removal mechanisms. In practice, the chemical and biological removal mechanisms each require favorable environments for activation. These environmental factors include oxygen availability, percentage of available organic matter, potential hydrogen (pH), salinity, and temperature. Please refer to the [[phosphorus]] and [[nitrogen]] pages for further details.  

Each LID practice has the potential to offer one or all the mentioned removal mechanisms. In practice, the chemical and biological removal mechanisms each require favorable environments for activation. These environmental factors include oxygen availability, percentage of available organic matter, potential hydrogen (pH), salinity, and temperature. Please refer to the [[phosphorus]] and nitrogen pages for further details.  

Additionally, proper maintenance of the LID practice in question is the key to maintain the removal capacity of the feature and ensure that it does not become an exporter of nutrients itself. A strategy common to all types of LID practices to avoid nutrient leaching is annual removal of accumulated sediment and debris from inlets.  For bioretention cells, bioswales and stormwater tree trenches featuring surface inlets and soil media, periodic removal of the top 2 to 5 centimetres of media in areas adjacent to inlets, and replacement with material that meets design specifications (e.g., every two years) has also been recommended.<ref> Johnson, J.P., Hunt, W.F. 2016. Evaluating the spatial distribution of pollutants and associated maintenance requirements in an 11 year-old bioretention cell in urban Charlotte, NC. Journal of Environmental Management. 184 (2016):363-370. https://www.sciencedirect.com/science/article/pii/S0301479716307812 </ref> <ref>Jones, P.S., Davis, A.P. 2013. Spatial Accumulation and Strength of Affiliation of Heavy Metals in Bioretention Media. Journal of Environmental Engineering. 139(4): 479-487. https://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EE.1943-7870.0000624 </ref>   

Additionally, proper maintenance of the LID practice in question is the key to maintain the removal capacity of the feature and ensure that it does not become an exporter of nutrients itself. A strategy common to all types of LID practices to avoid nutrient leaching is annual removal of accumulated sediment and debris from inlets.  For bioretention cells, bioswales and stormwater tree trenches featuring surface inlets and soil media, periodic removal of the top 2 to 5 centimetres of media in areas adjacent to inlets, and replacement with material that meets design specifications (e.g., every two years) has also been recommended.<ref> Johnson, J.P., Hunt, W.F. 2016. Evaluating the spatial distribution of pollutants and associated maintenance requirements in an 11 year-old bioretention cell in urban Charlotte, NC. Journal of Environmental Management. 184 (2016):363-370. https://www.sciencedirect.com/science/article/pii/S0301479716307812 </ref> <ref>Jones, P.S., Davis, A.P. 2013. Spatial Accumulation and Strength of Affiliation of Heavy Metals in Bioretention Media. Journal of Environmental Engineering. 139(4): 479-487. https://ascelibrary.org/doi/abs/10.1061/%28ASCE%29EE.1943-7870.0000624 </ref>