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Controls Influencing the Treatment of Excess Agricultural Nitrate with Denitrifying Bioreactors
Author(s) -
Pluer William T.,
Geohring Larry D.,
Steenhuis Tammo S.,
Walter M. Todd
Publication year - 2016
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2015.06.0271
Subject(s) - denitrifying bacteria , nitrate , bioreactor , agriculture , environmental science , denitrification , environmental chemistry , environmental engineering , pulp and paper industry , chemistry , nitrogen , ecology , biology , engineering , organic chemistry
Denitrifying bioreactors have been suggested as effective best management practices to reduce nitrate and nitrite (NO x ) in large‐scale agricultural tile drainage. This study combines experiments in flow‐through laboratory reactors with in situ continuous monitoring and experiments in a pair of field reactors to determine the effectiveness of reactors for small‐scale agriculture in New York. It also compares the use of a typical woodchip media with a woodchip and biochar mixture. Laboratory results showed linear increase in NO x removal with both increased inflow concentration and increased residence time. Average removal of NO x in weekly monitoring of field reactors over the course of two growing seasons was 3.23 and 4.00 g N m −3 d −1 for woodchip and woodchip/biochar reactors, respectively. Removal of NO x during two field experimental runs was similar to in situ monitoring and did not correlate with laboratory experiments. Factors that are uncontrollable at the field scale, such as temperature and inflow water chemistry, may result in more complex and resilient microbial communities that are less specialized for denitrification. Further study of other controlling variables, other field sites, and other parameters, including microbial communities and trace gas emissions, will help elucidate function and applicability of denitrifying bioreactors. Core Ideas Flow‐through lab reactors show a linear increase in NO x removal with residence time. Lab reactors show a linear increase in NO x removal at higher inflow NO x concentration. Field reactors significantly reduce NO x outflow from tile‐drained agriculture in NY. Field reactor experiment results do not follow linear inflow NO x trend found in lab. Biochar amendments show no significant removal of phosphorus in field reactors.