Diel fluctuations of high level nitrate and dissolved organic carbon concentrations in constructed wetland mesocosms

• Published in: Ecological engineering 2019-08, Vol.133, p.76-87
• Main Authors: Messer, Tiffany L., Birgand, François, Burchell, Michael R.
• Format: Article
• Language: English
• Subjects: Aquatic ecosystems; Artificial wetlands; Biogeochemistry; Carbon; Carbon cycle; Computer simulation; Diel cycling; Dissolved organic carbon; Drainage water; Ecosystems; High frequencies; High frequency; Mesocosms; Nitrate-N; Nitrates; Nitrogen; Spectrometers; Variation; Water circulation; Water column; Water quality; Water quality measurements; Wetlands
• ISSN: 0925-8574; 1872-6992
• DOI: 10.1016/j.ecoleng.2019.04.027

•High frequency monitoring of NO3-N and DOC were evaluated in wetlands.•Daily cycling of internal sources of N and C were observed in this study.•Observable NO3-N removal rates in wetlands may be limited by internal N sources. Portable in situ ultraviolet-visual spectrometers, through high frequency water quality measurements, provide new insight into biogeochemical processes occurring within dynamic ecosystems. Nitrogen and carbon cycling were observed in two distinct wetland mesocosm environments during a two-year mesocosm study. Simulated drainage water was loaded into the mesocosms across seasons with target nitrate-N levels between 2.5 and 10 mg L−1. Nitrate-N and dissolved organic carbon concentrations in the water column were measured hourly with the spectrometer and calibrated with water quality grab samples. Prominent and unique diel cycles were observed in both nitrate-N and dissolved organic carbon readings from the spectrometer, which reveal biogeochemical processes in these systems are more complicated than typically considered in empirical models. Findings support the importance of utilizing high frequency monitoring to advance current knowledge of nitrogen and carbon processes occurring in treatment wetland ecosystems.