| Suzhou River is one of the urban signs and is an important role in water ecosystems in Shanghai.Suzhou River began more than ten years of comprehensive improvement of the Suzhou River environment since 1988,and is a greater degree of improvement.At present,the mainstream of Suzhou Creek has basically eliminated the black and odor,the main water quality indicators remain in the V water standards(landscape water);However,due to the Suzhou River aquatic ecological restoration process is relatively slow and the ecosystem is more fragile,there will be short-term water pollution Black smelly phenomenon,a serious impact on the image of Shanghai.This paper is supported by Shanghai Environmental Protection Research Project,entitled "Study on Evaluation Index System of Suzhou Creek Ecological Risk Assessment and Ecological Restoration Monitoring"(No:201201072),and cooperating with Shanghai Environmental Monitoring Center.In order to analyze and evaluate water quality characteristics and Black-odor risk and pollution sources of Suzhou Creek,data collection and sampling research.the 1996?2015 water quality data,the 2013?2015 online monitoring data,the typical pumping station in 2013?2015,the river water quality sampling data of Suzhou Creek water are Organized and collected.Based on the single factor analysis,the TOPSIS model based on gray correlation,the pollution index method,the relative cumulative probability curve,the Pearson correlation analysis and the variance analysis,the black-odor evaluation methods proposed by the Ministry of Housing and Urban,The temporal and spatial characteristics of water quality and black-odor,the source of pollution were analyzed and evaluated.Thereby providing a basis for improving water quality of Suzhou Creek Suzhou Creek.(1)This paper analyzes the interannual water quality data of Suzhou Creek from 1996 to 2015 and the variation characteristics of monthly water quality data from 2013 to 2015.The results show that:?The trend of gradual improvement of Suzhou Creek water quality is divided into three periods:the water quality improvement period from 1996 to 2001,the overall stability of water quality from 2001 to 2010 has been repeated,and the improvement of water quality from 2011 to 2015 has been repeated.Suzhou River basic to meet the landscape water standards;? Suzhou Creek comprehensive water quality level can reach the V class water quality standards,But along Suzhou River,the comprehensive water quality level gradually reduced;?he weight index of dissolved oxygen,ammonia nitrogen,total phosphorus,permanganate index and biochemical oxygen demand of the Suzhou River were 23.4%,30.9%,25.8%,7.6%and 12.3%of the total weight,respectively.Ammonia nitrogen,dissolved oxygen and total phosphorus is the main indicator of Suzhou River water quality is not up to standard.(2)In order to comprehensively analyze the comprehensive water quality compliance rate and the water quality change of Suzhou Creek,Evaluation of Water Quality by Online Evaluation Based on Gray Relational Degree Based on TOPSIS Model.The comprehensive water quality compliance rate of the upstream Huashao section in 2014 and 2015 is 30.66%and 53.85%respectively,and the standard time is mainly concentrated in the winter and spring season,and the water quality of the autumn and summer season is relatively low.The comprehensive water quality of Kaixuan and Wuning Road in 2015 is 13.89%and 18.61%respectively.The water quality compliance rate of the upstream Huacao section is obviously higher than that of the downstream section.The variation trend of dissolved oxygen and ammonia nitrogen in the four sections is similar to that in the spring and summer season.(3)The spatial and temporal characteristics of black smelly in Suzhou Creek are analyzed and compared.The results show:?The method of evaluation of the black odor of the Ministry of Housing and the use of dissolved oxygen indicators can accurately reflect the Suzhou River black and black situation with objective and reasonable;?mild black smelly is more serious in Suzhou River,the mild black-odor time were measured in the total time of 32.1%,74.5%,73.4%respectively in Huacao,Kaixuan,Wuning section of Suzhou River;?There is a slight complication in the cross section of the Suzhou urban section,and the risk of mild blackness in the downstream section is greater than that in the upstream,due to the large amount of sediment in the drainage pipe and the influx of organic nutrients into the river and The water quality of the water body decreased,so that the water quality of the upstream water directly affects the quality of the downstream water quality;?There are two manifestations of heavy black smelly in the Suzhou River area:the first is the rapid recovery of the heavy water pollution caused by the rapid flow of water into the heavy black-odor and heavily polluted water mass,The second is the continued entry of pollution sources,that is,the pump station lead the river into the black state for a long time,long black smelly lead to severe black smelly after the end and will enter the light black-odor will not be rapid Return to normal level;?There is a significant correlation between the river and the black smoke in the coastal pumping station.In the spring and winter season,the single row of the river does not necessarily produce black smelly,the single season of the summer and autumn seasons,Spring and winter season for more than two consecutive days of overflowing river events will make the Suzhou River into the short-term intermittent mild black and smelly state.Severe black smelly occurred mainly in the flood season and two consecutive days of rainfall overflow event will increase the possibility of severe black smelly phenomenon.(4)The reasons for The quality of the Suzhou River is not up to the "V"water class and the black body of the water were analyzed:?The concentration of NH3-N and TP in the upstream were 2.1andl.1 times higher than that of the V water quality standard respectively.The concentration of NH3-N and TP in the downstream were 2.3andl.3 times higher than the standard of V water quality standard respectively.The concentration of CODMn,BOD5 and COD of the upstream and downstream water are better than those of the V class water quality standard,which is 1.5,0.25,0.5 and 0.38 times of the Grade V water quality standard.?The concentration of BOD5,COD and CODMn in the main tributaries of Suzhou River is slightly higher than that of the main stream,but the concentration value of tributaries is within the standard value of V water quality,and the contribution rate of water concentration is small,The DO concentration of the tributary is higher than that of the main stream,and the average concentration is about 2 times that of the mainstream.The influence of the water quality and the black odor on the Suzhou River is small.?The overflow of the Suzhou River is a key factor in the intermittent black-odor of the Suzhou River.BOD5 and COD are about 2 times before the release of the river,and the dissolved concentration is about 0.5 times of the standard value of the V class water quality. |
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