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Notice of RetractionPrediction of TP Concentration Threshold in Eutrophic Water Based on Grey Clustering Method

In this paper, a model based on grey clustering method is developed to evaluate the threshold of total phosphorus (TP) concentration in eutrophic water for guiding eutrophication control. Firstly, grey clustering method (GCM) and modified grey clustering method (MGCM) are introduced. Secondly, the model of the threshold of TP concentration is deduced. At last, Lake Taihu, a typical serious eutrophic lake in China, is selected as a case study area to testify the effectiveness of the model. The trophic states of Lake Taihu from 2001 to 2009 were evaluated to determine the management objective and the thresholds of TP concentration were calculated according to the objective in every two years from 2012 to 2020. The results show that Lake Taihu was always the upper-mesotrophic state from 2001 to 2009. When the management objective is set as the Meso-trophic state, the thresholds of TP concentration should be 0.0116, 0.0119, 0.0122, 0.0124 and 0.0126 in 2012, 2014, 2016, 2018, 2020, respectively. The result shows that TP-only control can be used in Lake Taihu to control eutrophication. The model provides the accuracy method to evaluate the threshold of TP concentration for controlling eutrophication. The model can also be used to other environmental problem to guide the corresponding pollution control.