Version 1
: Received: 5 June 2021 / Approved: 7 June 2021 / Online: 7 June 2021 (12:40:00 CEST)
How to cite:
Mohebbi, A.; Akbariyeh, S. Non-Parametric Analysis of Nitrogen Trends in the form of Nitrate and Nitrite in Rivers and Streams of the Contiguous United States for 1990-2019. Preprints2021, 2021060171. https://doi.org/10.20944/preprints202106.0171.v1
Mohebbi, A.; Akbariyeh, S. Non-Parametric Analysis of Nitrogen Trends in the form of Nitrate and Nitrite in Rivers and Streams of the Contiguous United States for 1990-2019. Preprints 2021, 2021060171. https://doi.org/10.20944/preprints202106.0171.v1
Mohebbi, A.; Akbariyeh, S. Non-Parametric Analysis of Nitrogen Trends in the form of Nitrate and Nitrite in Rivers and Streams of the Contiguous United States for 1990-2019. Preprints2021, 2021060171. https://doi.org/10.20944/preprints202106.0171.v1
APA Style
Mohebbi, A., & Akbariyeh, S. (2021). Non-Parametric Analysis of Nitrogen Trends in the form of Nitrate and Nitrite in Rivers and Streams of the Contiguous United States for 1990-2019. Preprints. https://doi.org/10.20944/preprints202106.0171.v1
Chicago/Turabian Style
Mohebbi, A. and Simin Akbariyeh. 2021 "Non-Parametric Analysis of Nitrogen Trends in the form of Nitrate and Nitrite in Rivers and Streams of the Contiguous United States for 1990-2019" Preprints. https://doi.org/10.20944/preprints202106.0171.v1
Abstract
Nitrogen and phosphorous support the ecosystem by supplying nutrients to algae and aquatic plants. Having them in excess results in the eutrophication of waters creating quality problems. In the past, nitrogen has been widely investigated for wells in the context of groundwater flow. However, a national-scale nitrogen assessment in rivers and streams has not received enough attention. In this research, the Wilcoxon rank sum test, as a non-parametric hypothesis testing method, has been applied to nitrogen concentration in the form of nitrate-nitrogen and nitrite-nitrogen in rivers and streams of the Contiguous United States. This approach was particularly selected because of the non-normal and positively skewed nitrogen levels occurring in the surface flow. This method was able to identify the impaired body of waters as well as quantify the confidence, significance, and errors involved. The Northern Appalachians (NAP), Northern Plains (NPL), and Xeric (XER) ecoregions were worsening in the nitrogen-nitrate condition with NAP, and XER needed immediate actions. The nitrite-nitrogen condition did not pose an immediate threat, so mitigation plans should focus more on nitrate-nitrogen remediation. It was shown that the method was superior to the two-sample t-test by yielding lower type II errors.
Keywords
Nitrate-Nitrogen; Nitrite-Nitrogen; Non-Parametric Hypothesis Testing, Type II Error, Rivers and Streams
Subject
Engineering, Civil Engineering
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.