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| Influence of decomposition processes of higher aquatic plants and algae on water quality near the shoreline of Lake Taihu |
| Received:August 30, 2017 Revised:October 16, 2017 |
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| KeyWord:aquatic plants;cyanobacteria;decomposition;water quality;Lake Taihu |
| Author Name | Affiliation | E-mail | | YU Cen-cen | School of Environment, Nanjing Normal University, Nanjing 210023, China | | | MA Jie | School of Geography Science, Nanjing Normal University, Nanjing 210023, China | | | XU Xiao-guang | School of Environment, Nanjing Normal University, Nanjing 210023, China
Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application Jiangsu Key Laboratory of Environmental Change and Ecological Construction, Institute of Water Environmental Eco-remediation, Nanjing 210023, China | | | WANG Guo-xiang | School of Environment, Nanjing Normal University, Nanjing 210023, China
Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application Jiangsu Key Laboratory of Environmental Change and Ecological Construction, Institute of Water Environmental Eco-remediation, Nanjing 210023, China | wangguoxiang@njnu.edu.cn | | LIU Hui-chao | School of Environment, Nanjing Normal University, Nanjing 210023, China | |
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| Abstract: |
| Cyanobacteria and Phragmites australis from Lake Taihu were collected to simulate the influence of decomposition processes of higher aquatic plants and algae on water quality in the laboratory. Cyanobacteria, Phragmites australis, and cyanobacteria and Phragmites australis samples of 2 g each were arranged into groups B, C, and D, respectively, for three treatments to continuously monitor the concentration variations of total nitrogen(TN), total phosphorus(TP) and other physico-chemical parameters of water. Results showed that DO and Eh rapidly decreased after adding cyanobacteria and aquatic plants. The mixed decomposition group remained anaerobic throughout the experiment, and Eh values of the water body were finally stabilized at about -150 mV, suggesting that the water was in a strongly reducing state. Simultaneously, the strong anaerobic and reducing environments accelerated the decomposition of cyanobacteria and Phragmites australis, and promoted the release of nutrients to the overlying water. The TN contents of B, C, and D groups peaked on the 2nd, 7th, and 2nd days, and their maximum concentrations were 5, 2 times, and 6 times that of the control, respectively. Inorganic nitrogen was dominated by NH4+-N. Under anaerobic conditions, the migration and transformation of phosphate from the interstitial water to the overlying water and the reduction of Fe-P in the sediments increased the concentrations of TP and Fe2+ in the water. The average increasing rates of TP were 0.38, 0.10 mg·L-1·d-1, and 0.52 mg·L-1·d-1, and the highest concentration of Fe2+ was 1.62 mg·L-1. These observations clarified that a large amount of nutrients was released during the decomposition processes of higher aquatic plants and algae, which intensified eutrophication. Therefore, it is necessary to pay close attention to reeds and the shoreline of eutrophic lakes to avoid rapid deterioration of water quality. |
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