NUMERICAL SIMULATION AND EUTROPHICATION ASSESSMENT OF SPATIOTEMPORAL DISTRIBUTION OF NITROGEN,PHOSPHORUS,AND CHLOROPHYLL CONCENTRATIONS IN THE BOHAI SEA
At present,the risk of eutrophication in the Bohai Sea remains high,seriously constraining the sustainable development of the social and economic environment around the Bohai Sea.Conducting assessment and trend analysis of nearshore eutrophication is required for national ecological security.However,the difficulty lies in obtaining high-quality data on the long-term evolution process of eutrophication assessment elements.Based on the HAMSOM marine ecological model,we constructed a three-dimensional hydrodynamic/biogeochemical coupling model suitable for eutrophication assessment and conducted trend analysis for the Bohai Sea by modifying the degradation kinetics of dissolved organic nitrogen(DON)as a difficultly/easily degradable component.The model was calibrated using the survey results of DON,dissolved inorganic nitrogen(DIN),dissolved inorganic phosphorus(DIP),and chlorophyll a(chl a)in four seasons of 2019 in the Bohai Sea.The model was validated using long-term survey results from 1980 to 2020.Results show that the simulation results agree well with the survey results in terms of numerical magnitude and trend.The relative standard deviation,similarity coefficient,and Kappa coefficient are 24％,0.77,and 0.60,respectively.The nutritional quality index(NQI)was calculated using long-term evolution process data of DIN,DIP,DON,and chl a simulated by the model.The results indicate that the current eutrophication status of the Bohai Sea is generally in oligotrophic state,while in eutrophic state in the coastal waters of the Bohai Bay,Liaodong Bay,and Laizhou Bay but in mesotrophic state from May to October.In long-term view,the overall eutrophication status of the Bohai Sea tended to improve.The compound eutrophication index(CEI)shows that the eutrophication assessment results calculated by CEI are quite consistent with those calculated by NQI,with a similarity coefficient of 0.83.The eutrophication assessment method established in this study has high reliability and can be used for eutrophication assessment in the Bohai Sea.
the Bohai seaecological modelassessment of eutrophicationnumerical simulation
万方数据
维普
