| With the rapid development of urbanization and industrialization,a large population has grown,and a large amount of domestic garbage and industrial pollutants have gathered in the ocean in various forms,which has made marine water heavy metal pollution increasingly serious.As one of the major environmental pollutants in the ocean,heavy metals have strong biological toxicity and are easy to accumulate in organisms,which not only poses a serious threat to the marine ecological environment,but also poses great harm to marine life and human health.Since the 1950 s,heavy metals have received close attention from people and have been one of the research focuses of the marine environment.At present,the research on heavy metals in the mouth area of the Yangtze River estuary is mainly the study of the spatial changes of heavy metals.There are few studies on time series,and the study of time series basically considers the study area as a whole.The study of time-varying characteristics and model prediction were carried out.The contents of five heavy metals Cu,Zn,Pb,Hg and As in the water bodies of the North Branch,South Branch and North Port of the Yangtze River Estuary from 2004 to 2017 were measured and analyzed.The differences were studied,and the differences in heavy metal content between the coastal areas of Shanghai and the mouth of the Yangtze River were compared and analyzed.A comparative analysis of the difference in heavy metal content between the coastal area of Shanghai and the mouth of the Yangtze River estuary;correlation analysis of five heavy metals in water and water temperature,salinity,p H,DO,sewage discharge and environmental treatment.Correlation between factors;based on the ARIMA model based on water and heavy metals in the mouth of the Yangtze River estuary from 2004 to 2017,a time series prediction model of water and heavy metals in the Yangtze River estuary was established to predict and analyze the heavy metal content of the Yangtze River estuary in the next few years.The change trend of the data was predicted,and the accuracy of the data was further verified.Concluded as follow:(1)Heavy metals such as Cu,Pb,Zn,and As are greatly affected by coastal discharge.With the development of society,people are paying more and more attention to environmental pollution issues,measures to reduce emissions,and other measures,and the frequency of major domestic pollution accidents from the beginning Hundreds of cases have been reduced to 14 cases in 2017.The sudden pollutant leakage situation has obviously improved,which has reduced the heavy metal content in the Yangtze River estuary,and the emission of Hg pollutants has not decreased during these years,so the Hg content has not appeared The obvious increase and decrease is relatively stable,and the implementation of a large number of pollution control and management methods has effectively reduced the discharge of pollutants,making the overall trend of heavy metals showing a downward trend.(2)In terms of seasonal differences,the contents of Cu,Zn,and Pb in the water body are higher in summer in the North Port Beisha and the North Branch Beigang than in the autumn and winter seasons.In the North Branch,the seasonal characteristics of these three heavy metals are opposite.It shows that winter is higher than summer.The seasonal characteristics of the three regions of As are all higher in winter than in summer.The seasonal characteristics of Hg in the three regions are higher in summer than in autumn and winter.(3)Correlation analysis shows that there is no significant correlation between environmental factors and heavy metal content in the time series,but at a certain point in time,the relationship between environmental factors and heavy metal content at different sites,Cu in the water body is significantly positively correlated with temperature,and salinity There is a very significant negative correlation,Zn and As are significantly negatively correlated with temperature,Hg is significantly negatively correlated with salinity,Cu is significantly negatively correlated with dissolved oxygen(DO),and no metals that are correlated with p H are found.(4)With the development of the economy and the treatment of environmental problems during the multiple five-year plans,the investment in pollution control has increased from 190.98 billion yuan to nearly 100 billion yuan in 14 years.As the investment in environmental problem management increases,heavy metals The content generally shows a downward trend and has a significant negative correlation with governance investment.Altho?gh the correlation with pollutant emissions is not significant,the amount of pollutants has a great impact on the small changes in heavy metals in certain years.The change of heavy metal content in the environment is the result of the combined effect of pollutant discharge and treatment investment.Under the premise of controlling the discharge of pollutants at a stable level,gradually increasing the investment of environmental treatment can effectively reduce the heavy metal content in the environment.The distribution of heavy metals in the coastal area of Shanghai is that the content of heavy metals in the waters near the shore is higher than that in the areas farther away from the shore.It is the main source of heavy metal pollution in the Yangtze Estuary.(5)According to the differences in environmental factors such as the North Branch of the Yangtze Estuary,the North Branch of the South Branch,and the North Sand and North Sand,the distribution of heavy metal content was different.Based on the data from 2004 to 2017,the water heavy metal content in the three regions of the Yangtze River estuary area were established respectively.The prediction model and standardized residual analysis showed that the data showed a normal distribution.The average errors of the five heavy metals in the three areas of North Branch,South Branch Beigang and Beigang Beisha were respectively: Cu: 0.879?g / L,Zn: 2.357?g / L,Pb: 0.205 ?g / L,Hg: 0.055 ?g / L,As: 0.195 ?g / L;Cu: 0.352 ?g / L,Zn: 1.546 ?g / L,Pb: 0.112 ?g / L,Hg: 0.028 ?g / L,As: 0.194?g / L;Cu: 0.459?g / L,Zn: 2.102?g / L,Pb: 0.185?g / L,Hg: 0.020?g / L,As: 0.194?g / L,the error is small,the prediction is more reliable,Using this model to predict the water heavy metal content of the Yangtze River estuary from 2020 to 2022,it is predicted that the heavy metal content in the three areas at the mouth of the Yangtze River estuary is low,and the seasonal differences and change trends are basically consistent with the measured data and have a high The accuracy of the zoning prediction study of the Yangtze River Estuary can reflect the heavy metal content and variation characteristics of different regions,can provide more targeted and more reflective prediction data that can reflect the regional characteristics,and provide a certain theoretical basis for the formulation of future heavy metal governance programs. |
PDF Full Text Request