| Polychlorinated biphenyls(Polychlorinated,biphenyls,PCBs)are highly toxic and difficult to degrade organic pollutants.They are very harmful to humans and living organisms.PCBs pollution incidents in Japan and Taiwan have had a significant impact,so it is necessary to research it.The PCBs in the environment continues to spread around the globe in water,atmosphere,and organisms accumulate.It is a global problem.Therefore,the Stockholm convention lists let it be one of the global persistent organic pollutants.Our country stopped using PCBs in 1975.The Changjiang Estuary is the largest estuary in China,which is the third largest estuary in the world,with a dense population and concentrated economic activities.Therefore,the environmental risk assessment of this region is particularly important.The study area is in 121°E~123°E and 30.5°N~31.8°N,using analysis and treatment from 2001 to 2016(except 2009 data)15 years of continuous data,having a more thorough understanding on the distribution of PCBs in the Changjiang River Estuary and its adjacent waters,through principal component analysis of the components and sources of pollution,using toxic equivalent factor method(Toxic equivalency factors,TEFs)and the potential ecological risk index(Potential Ecological Risk Index,PERI)on the ecological evaluation.The results show that:1.Interannual variability of PCBs during 2001-2016 In 2001,the numerical changes were mainly descending from west to east.The high value area appears on the north shore of Hangzhou Bay,near the coast of Jinshan,at the same time in the waters near the Liuhe appeared high value.In 2002,the numerical changes were mainly offshore and the higher the value.The highest value appears on the north shore of the Hangzhou Bay,near the Jinshan sea,and the second highest values near the Changjiang River and the sea mouth.In 2003,the numerical changes were mainly offshore,and the higher the value.The highest value appeared in the waters near the Shengsi islands east of wolfberry Shengzhou Island,in the north also has a high value area,the trend of the changes of the waters near the north shore of Hangzhou Bay is the same,this is a year of relatively high value.Baoshan Liuhe waters along the Changjiang River in the numerical reduction.In 2004,the change of the numerical value was mainly from the high value of the sea area in the east of the nine section of sand,descending in the east of the nine section of sand,and there was a high value area in the southeast of the Shengsi archipelago.In 2005,the numerical changes were mainly centered on the sea area north of the Shengsi archipelago.The outward values were higher and higher,which generated high values in the waters near Baoshan along the Changjiang River,and produced sub high values in the waters near Jinshan and Jiaxing.In 2006 the main numerical changes for the formation of a high value area in the nine sand sea,then descended,the formation of a high value area in Hengsha Island and nine sand,then descended.This is similar to the distribution map of 2004.In 2007,the numerical variation mainly occurred in the North Branch of the Changjiang River and the sea area near Qidong,and decreased successively in the south,and the secondary value appeared in the sea area near the mouth of Nanhui and decreased successively.A high value area is also found in the waters north of the Shengsi archipelago.In 2010 two extremal region in the southeast and Hengsha Island Southeast of Qidong,in the Shengsi Islands waters north high value area.In 2011 the high value appeared mainly in the Shengsi archipelago,in the southeast of Hengsha Island also has two high value area.In 2012,the highest value in the southeast of Qidong sea,between nine and Hengsha Island in the South China Sea sand and Jinshan domain high value.In 2013,the highest value appeared in the southeast of the nine section of the sand,and in the waters east of the mouth of Nanhui,the value of Xu six river on the Changjiang River was increased.In 2014,the highest value appeared in the Jinshan sea area on the north coast of the Hangzhou Bay,and the value of the Shengsi Archipelago Sea area remained unchanged.In 2015,the highest value appeared in the six Jing River waters along the Changjiang River,while the other sea areas changed little.In 2016,the highest value in the Changjiang River port waters,high value appeared in the Changjiang River and the Shengsi Islands waters six Xu Jing in the waters near Shengsi island.2.Spatial distribution of PCBs(1)The North Bank of Hangzhou Bay Sea area,most of the year value is in the range of 0-4ng/g,the exception of 2001,the range of 15-21ng/g;in 2012,the range of 5-20ng/g;in 2014,the range of 3-13ng/g;in 2016,the range of 8-20ng/g.It is mainly affected by the discharge of wastewater from the chemical plant along the gold coast.(2)The Shengsi Islands sea area,most of the year value is in the range of 0-3ng/g,the exception of the year is 2011,the average value of 17.1ng/g;in 2012,the range of 4.18-18.5ng/g;in 2013,in the range of Shengshan archipelago waters surrounding the Gouqi island is 3-5ng/g,around the island of Shengsi does not exceed the scope of the 0-3ng/g;in 2016,the range of 12-31ng/g,the main index in Shengsi the island of Shengzhou Island high ratio.This region may be mainly affected by the Taiwan warm current and the Changjiang River diluted water,and it does not exclude the influence of human activities.(3)East of Qidong(South)area,most of the year value is in the range of 0-5ng/g,except for the year 2012,the range of 10-55ng/g,the range of 5-11ng/g,2014,2016,the range of 12-20ng/g,may affect the abandoned the Yellow River delta sediment is mainly affected by the the Yellow Sea coastal current carrying along Jiangsu coast and anthropogenic emissions of sewage the.(4)East of Nanhui and southeast of Hengsha island,part of the year in the range between 0-10ng/g,except for the year 2004,the range of 4-16ng/g;in 2011,the range of 9-15ng/g,in 2012 2016,the range of 10-20ng/g,the range of 12-28ng/g,may be mainly affected by the runoff of the Changjiang River and the Changjiang River,there are also some the influence of human coastal pollution.(5)Waters along the Changjiang River,the values range between about 0-5ng/g in 2012 and 2016 is Wusong waters high value,may be influenced by the Huangpu River and the Changjiang River and the dual role of human activities.In 2015,the water area in Xu six Jing River area was high,mainly affected by the Changjiang River runoff.3.The main PCBs monomer is CB28,CB52 and CB180 in surface sediments of 2016,the average value of the total CB28 accounted for 30.14%,the average content of 2.14ng/g,CB52 in the total in most with 68.46%,the average value is 15.45%,the average content of 2.419ng/g,CB180 accounted for the average total amount is 35.77%,the average content is 2.338ng/g.4.The content of TEFs on the PCBs 2016 Changjiang River Estuary and its adjacent waters in the surface sediments of the risk assessment,can get the toxic equivalent of PCBs in surface sediments in the region of 0.014~0.785ng/g,PCBs in Changjiang River Estuary and its adjacent waters in the surface sediment toxicity when the amount is in medium level;the PERI content of PCBs from 2001 to 2016 in the Changjiang River Estuary and its adjacent in surface sediments,the risk assessment of PCBs content in surface sediments in the region is mainly secondary ecological harm,but in a few years of strong ecological harm and strong ecological harm.5.In 2016 monomer data were analyzed by principal component analysis,the content of PCBs in surface sediments of the Changjiang Estuary and adjacent waters in three and five PCBs and PCBs,and accompanied by a certain amount of carbon and seven PCBs,the main source of power is the container impregnating agent,paint additives,industrial in transformer oil leakage and making the paper industry emissions,and seven PCBs and hexachloro may formed by atmospheric deposition after degradation. |
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