Fluctuation of phosphorus concentration in Lake Taihu in the past 70 years and future control strategy

??????????????????????????????????????????.?????????70???1949—2020?????????????????????????????????????????????????????????????????????????.????????1950??????????????30????????????????????.????????????????????????????????????????????????????????????????.?20???????????????????????1998?????????“????”?2007?????????????????????2017?????????????????????????????.?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????.?70?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????.;Understanding the changing mechanism of phosphorus concentration in lakes is precondition strategic decision for lake restoration. Based on 70 years (1949-2020) monitoring data at Lake Taihu, a large shallow lake, it found that was highly fluctuated temporally and spatially, owing to both human pollution natural limnological changes. Phosphorus concentrations largely different relatively clean 1950 polluted recent 30 years. Heavy rain storm discharge plenty external into causing spatial difference water concentration. Strong wind lots released from sediment, temporal fluctuation And algal bloom materials re- distribution by driving also bring about uncertainty concentrations. In 20 years, abatement projects have significantly changed spatial-temporal change Taihu. Zero Action control Taihu catchment since 1998, resource diversion engineering 2007, situation aggravate 2017 influenced intensity, mean value However, whole still keep high level even treatment investigation. Its reasons are loading factors, such as increase construction land use ratios, population increases, crop planting structure farmlands, internal submerged vegetation degradations, hydrological changes, aggravates under climatic change. The seventy variation characteristic should provide lessons management. Relatively nature lakes. Decision-maker consider when they formulate protection target External give priority, adjustment basin deeply removal tail-water urban sewage plants. At same time, measures, restoration top-down food-web biomass bio-manipulation fishery be undertaken make sure being controlled.