Journal article
Estimating nitrate-nitrogen retention in a large constructed wetland using high-frequency, continuous monitoring and hydrologic modeling
Ecological engineering, Vol.117, pp.69-83
07/2018
DOI: 10.1016/j.ecoleng.2018.03.014
Abstract
•Wetland nitrate retention was quantified using high frequency in situ nitrate sensors.•A physically-based hydrologic model estimated discharge for NO3-N loading calculations.•The wetland reduced NO3-N concentrations 49% and loads 61 kg day−1 from May–Nov over a 3-yr period.•Wetland NO3-N mass retention was highest in Jun and removal efficiency was highest in Aug.•High-frequency monitoring captured NO3-N dynamics not possible with traditional grab sampling.
Wetlands are an effective edge-of-field conservation practice for reducing agricultural nitrate-nitrogen (NO3-N) loads, but their removal performance varies with hydrologic conditions and other factors difficult to capture with traditional grab sampling schemes. We quantified NO3-N retention in a large Iowa constructed wetland using high-frequency (15-min) in situ NO3-N sensors and a physically-based hydrologic model that estimated discharge. Monitoring from May–Nov over a 3-yr period (2014–16) indicated the wetland reduced incoming NO3-N concentrations 49% and loads by an estimated 61 kg day−1 (0.48 g m−2 day−1 based on wetland area removal). Monthly and seasonal (May–Nov) wetland retention performance were significantly influenced by hydrologic conditions, as NO3-N concentration reductions ranged from 23% in a year that received nearly 50% more seasonal precipitation than average (2016) to 59–65% in years that received average seasonal precipitation (2014–15). On a monthly basis, NO3-N mass retention was highest in Jun when NO3-N loading was highest, while retention efficiency – the percent of the incoming NO3-N load retained by the wetland – was highest in Jul and Aug when water temperature and hydraulic residence time were higher. The high-frequency monitoring captured NO3-N dynamics not possible with lower-frequency sampling. Extrapolating the May–Nov 3-yr average wetland NO3-N retention estimated in this study to a much larger scale, over 5600 wetlands treating more than 60% of Iowa’s area and totaling an estimated $1.5 billion in design and construction would be required to reduce the state’s baseline NO3-N load by 45%, indicating the sizable investment in wetland construction and restoration needed to achieve Gulf of Mexico Hypoxia water quality goals.
Details
- Title: Subtitle
- Estimating nitrate-nitrogen retention in a large constructed wetland using high-frequency, continuous monitoring and hydrologic modeling
- Creators
- C.W Drake - University of IowaC.S Jones - University of IowaK.E Schilling - University of IowaA Arenas Amado - University of IowaL.J Weber - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Ecological engineering, Vol.117, pp.69-83
- Publisher
- Elsevier B.V
- DOI
- 10.1016/j.ecoleng.2018.03.014
- ISSN
- 0925-8574
- eISSN
- 1872-6992
- Grant note
- DOI: 10.13039/100000199, name: USDA-CIG; DOI: 10.13039/100009227, name: Iowa State University
- Language
- English
- Date published
- 07/2018
- Academic Unit
- Earth and Environmental Sciences; IIHR--Hydroscience and Engineering; Civil and Environmental Engineering
- Record Identifier
- 9984197519702771
Metrics
9 Record Views