Study On The Influence Of Shipping On The Water Environment Of The Typical Channel Of Taihu Lake And Model Research

Taihu Lake Basin is located in the plain of the middle and lower reaches of the Yangtze River,with dense river network.Inland water transportation has always been the main transportation mode in this area.With the in-depth implementation of the comprehensive water environment management plan of Taihu Lake Basin in our province,the pollution discharge from ships and its environmental impact on inland river waters have gradually become the focus of social attention.The discharge of nitrogen and phosphorus pollutants from domestic sewage and washing water into the river may lead to the increase of nitrogen and phosphorus content in the regional water body,thus adversely affecting the eutrophication of Taihu Lake basin.It is an important research topic to study and carry out the prevention and control of the pollution from the moving source of ships in the Taihu lake basin,to solve the pollution from ships in the Taihu lake,to protect the river environment,to realize the sustainable development of the shipping industry,and to connect with the environmental protection of the world water transportation.In this paper,through field investigation,sampling and monitoring methods,the navigation status of the main river into the lake,the ship pollution prevention status,the river surrounding pollution sources and land use status,the river water quality status,etc.,and the ship pollution load analysis and water environment carrying capacity analysis.On this basis,based on water quality control monitoring,SPSS correlation analysis,curve fitting and other methods,the influence of shipping on the water quality of typical rivers entering the lake was systematically analyzed.Finally,the correlation model of water environment carrying capacity and ship pollution was established.The research conclusions mainly include the following aspects:（1）Among the 15 main rivers of Taihu Lake,only Chendong Port,Taige Nan Canal,Taige Nan Canal,Wujin Port,Zhihu Port and Wangyu River are channels of the current level;In terms of vessel flow,the navigable vessel flow of Chendong Port and Wangyu River is larger,followed by Zhihu Port,and the navigable vessel flow of Tai Ge Canal,Tai Ge Nan Canal and Wujin Port is smaller.In terms of vessel types,cargo ships are the main navigable vessels entering the lakes and rivers,accounting for more than 98%,and more than 93%are vessels with a gross tonnage of less than400 tons.In terms of pollution prevention and control of inland river ships,almost all ships with a gross tonnage of more than 400 tons are equipped with domestic sewage treatment equipment,oil and water separators and dirty oil tanks（cabinets）;Domestic sewage treatment equipment has not been installed on inland river vessels under 400 gross tons,but oil and water separation equipment and sewage oil tanks（cabinets）have been installed.Inland river ships are basically equipped with garbage bins,garbage collected by the shore centralized treatment,basically can do not discharge ship garbage to the inland waters;In terms of the pollutant load of ships in major navigable rivers,Wangyu River has the largest total discharge of sewage and major pollutants,followed by Chendong Port.Zhihu Port,Wujin Port,and Taigeo Canal and Taigeo South Canal have smaller total discharge of sewage and major pollutants due to the smaller discharge of ships.In addition,considering that inland river ships are basically equipped with garbage bins,the collected garbage is handed over to the shore for centralized disposal,so the impact caused by ship household garbage discharge is no longer considered.It is concluded that ship pollution is not the main factor of water quality deterioration and eutrophication in Taihu Lake.（2）In terms of the water environment status of typical rivers entering the lake,the main pollution sources are domestic pollution and agricultural pollution;The main sources of pollution in Dapu Port are industrial pollution,domestic pollution,agricultural pollution and aquaculture pollution.The annual inflow of COD,NH₃-N,TP and TN in Dapu Port is larger than that in Chendong Port.From 2016 to 2019,NH₃-N and total nitrogen in Chendong Port met the 2020 target requirements in the《National Overall Plan for Taihu Lake Management》.The permanganate index and the concentration of total phosphorus exceeded the standard,while the concentration of total phosphorus in Dapu Port exceeded the standard,while the other indicators met the target requirements.The permanganate index and total phosphorus water environmental capacity of Chendong Port exceed the standards of 0.25 t/d and 0.12 t/d respectively,the total phosphorus water environmental capacity of Dapu Port exceed the standards of 0.02 t/d,and the contents of other pollutants are within the river environmental capacity.（3）The correlation main rivers into the lake water quality and Marine shipping relations,Chendong Port sludge effective phosphorus and navigation of ship traffic at the 0.01 level significantly negative correlation,the rest of the pollutant index difference due to different land outside of river pollution sources,and the same river pollution in different periods,ship correlation relationship between flow and water quality of main pollutant indexes is not obvious.（4）Using COIM model to forecast the water environmental capacity looking Wangyu River and Chendong Port can accommodate the ship quantity is more than four times the size of the existing ship,that means looking at port Chendong Port and Wangyu River ship years under the situation of steady flow,Marine pollution caused by the effects in the aquatic environment is small and simple ship size prediction in a relatively long period of time can be a good development;The main ways to improve the carrying capacity of river water environment are as follows:strengthening the construction of sewage treatment facilities,reducing the intensity of land and upstream pollution discharge sources,perfecting the construction of pollutant discharge permit system;Improve the local sewage treatment process and speed up the construction of reclaimed water reuse project,improve the efficiency of sewage treatment in this area,and raise the threshold of entering the river;Timely increase the upstream water intake to reduce the concentration of pollutants through dilution degradation;We should strengthen supervision over vessels operating in the river,install sewage treatment units,oil-water separators and other devices in batches,eliminate old and small vessels,and formulate a strict ship inspection system.