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| Long-term effects and influencing factors of nitrogen retention in a surface flow constructed wetland in the northern part of Erhai Lake |
| Received:December 01, 2019 |
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| KeyWord:surface flow constructed wetland;nitrogen retention;long-term effect;Erhai watershed |
| Author Name | Affiliation | E-mail | | LIANG Qi-bin | College of Ecology and Environment, Southwest Forestry University, Kunming 650224, China | | | HOU Lei | College of Ecology and Environment, Southwest Forestry University, Kunming 650224, China | | | LI Neng-fa | College of Ecology and Environment, Southwest Forestry University, Kunming 650224, China | | | CHEN Xin | College of Ecology and Environment, Southwest Forestry University, Kunming 650224, China | | | WANG Ke-qin | College of Ecology and Environment, Southwest Forestry University, Kunming 650224, China | wangkeqin7389@sina.com |
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| Abstract: |
| Taking the Luoshijiang estuarine wetland, which was constructed 10 years ago in the northern part of Erhai Lake, as the study target, the dynamic change in nitrogen retention in the restored wetland in the Erhai watershed for 1, 5, and 10 years and its influencing factors were evaluated based on one-year in-situ monitoring and literature research. The results showed that:The concentration of inorganic nitrogen in the overlying water of the Luoshijiang estuarine wetland differed significantly between the dry and wet seasons; the concentration of inorganic nitrogen in the dry season was significantly higher than that in the wet season(P<0.05). The average concentrations of TN, NH4+-N, and NO3--N in the wetland inlet were 3.34, 0.75 mg·L-1, and 0.77 mg·L-1 respectively, and those in the wetland outlet were 2.01, 0.42 mg·L-1, and 0.45 mg·L-1 respectively, indicating that the Luoshijiang estuarine wetland was still capable of retaining nitrogen after 10 years of normal operation. The average TN, NH4+-N, and NO3--N retention efficiency of the restored wetlands in the northern part of Erhai Lake after 1, 5, and 10 years of normal operation showed a decreasing trend, but the difference did not reach a significant level(P>0.05). The efficiency of nitrogen retention in the restored wetlands with different operation periods also varied with dry and wet seasons. The retention efficiencies of TN, NH4+-N, and NO3--N in the Luoshijiang estuarine wetland after 10 years of operation were 37.2%, 34.6%, and 29.2%, respectively. Redundancy analysis(RDA)and Pearson correlation analysis revealed that the ranges of DO, ρ(NH4+-N), COD/TN, and temperature were beneficial to the nitrification process, but detrimental to the denitrification process. Thus, subsequent restoration, construction, and management of wetlands in Erhai Lake should focus on the optimization of the denitrification process of the overlying water to enhance the efficiency of nitrogen retention. |
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