| The Yangtze is China’s first river,the total length of about 6397 km, flowing through 11 provinces(autonomous regions and municipalities), the body of water is not only an important source of drinking water, but also to promote the development of the Yangtze River economic belt. Three Gorges Project has attracted worldwide attention, even stable economic status of the Yangtze River. In recent years,Petrochemical, mining, power, energy and other industries continue to grow along the river, most of the waste water untreated or non-compliance directly into water bodies,resulting in Water Pollution, seriously affecting the safety of drinking water. Three Gorges reservoir area is an important repository of freshwater resources, water quality and safety relationship to the national economy. In the 1990 s, the state began implementing project to improve the ecological environment in the reservoir area and the Yangtze River comprehensive, but there are still outstanding issues. The upper of the Yangtze River(Yibin to Luzhou) section is a direct water source supply area of the Three Gorges Reservoir, upstream of the reservoir area is also an important node in the city, the water quality is directly related to the safety of drinking water reservoir.Therefore, this article on the upper reaches of the Yangtze(Yibin to Luzhou) water quality and surface sediments were analyzed and evaluated, Tuojiang, Minjiang,Yongning River, South River and Changning river Irie cross section of concerns,heavy metals in water and sediments Cd, Cr, Cu, Ni, Pb, Zn and other 40 kinds of elements and 16 PAHs as the main object of study, analyze the content composition,characteristics and sources of pollution, and risk assessment. The results of this paper are listed below.(1) The heavy metal elements which polluted the upper reaches of the Yangtze River section of Yibin to Luzhou of the main branch and the main river branch section were Pb、Ti、Mn and Fe, which concentrations referre to Surface Water Environmental Quality(GB3838-2002) Ⅱ class standards and centralized drinking surface water source required standard limits. In grievances period, heavy metals were mainly presenced at dissolved, In the dry season, heavy metals were mainly presenced at suspended. From the spatial distribution point of view, on the whole, heavy metal pollution of Luzhou more serious than Yibin section, heavy metal pollution of Tuojiang was more serious than other sections. The three carcinogens of As, Cd, Cr caused Personal Risk were 1.0 × 10-6 which between Sweden, the Netherlands,the United Kingdom(1.0×10-4)and the United States(5.0 × 10-5). ecommended maximumacceptable risk level 1.0 × 10-4 and 5.0 × 10-5. Not constitute a threat to human health.(2) There are 16 kinds of PAHs in the upper reaches of Yangtze rive of Yi Bin to Lu Zhou and its content were 0.064-1.15ug/L.Meets our country centralized drinking water and surface water limits by 2ug/L.PAHs were given priority to with low central.The maximum concentration of Benzopyrene with strongest carcinogenicity is0.02014 ug/L,which is far more than concentration of drinking water surface water regulation(CJ/T206-2005) in our country centralized standard limit(0.0028 ug/L).What is more, more than 70% sample point content of benzopyrene exceed levels of standard limit. Source analysis and principal component analysis showed that pollution sources come mainly from oil source, the combustion source and traffic pollution. Health risk assessment showed that the risk coefficient of each sampling points in 10-9 orders of magnitude, does not constitute a risk to human health.(3) The average concentration of heavy metals that were Cd、Sn、Ti、Fe、Ta、Cr、Mn、Co、Ni、Cu、Zn、Mo、Sb、Pb、W, which content were 0.76 mg?kg-1、3.67 mg?kg-1、7.45 mg?kg-1、51.04 mg?kg-1、1.90 mg?kg-1、78.77 mg?kg-1、619mg?kg-1、15.94 mg?kg-1、34.52 mg?kg-1、42.92 mg?kg-1、98.93 mg?kg-1、0.98 mg?kg-1、3.67 mg?kg-1、1.20 mg?kg-1、35.41 mg?kg-1、2.65 mg?kg-1in water body sediment of Yibin to luzhou of Yangtze river section. Among them,the pollution of Cd in the yibin section and Yong Ning He upstream is most serious;followed by, has more than 15 times of soil background values. In the minjiang river section and yibin city section.Enrichment coefficient method show that Cd have serious human input, enrichment coefficient is being between 2.7 to 15.7, is considered to be severe pollution.Followed by, the enrichment coefficient of the heavy metal elements Ti is between 1.5to 13.4 in each branch into the river section and luzhou section the Yangtze river that,to input is as the main sources of pollution. Individual potential ecological risk index(Eri) shows that the Cd is the high ecological risk levels, the rest of heavy metals are in slight pollution levels. Integrated ecological risk index showed that section into Minjiang river and Tuojiang river were a strong level of risk. The level of risk in the Yangtze river yibin section is greater than the luzhou Yangtze river section.(4) The amount of 16 of the PAH’s in main tributaries of Yibin to luzhou section of the Yangtze river upstream river sediment were 5.071 to 9.324mg/kg,with a mean of 7.00 mg/kg.The average concentration of Acenaphthylene, benzo(a) anthracene,benzo(a) pyrene, indeno(1,2,3-cd) pyrene and benzo(g, h, I) perylene were 2.22mg/kg、0.42 mg/kg、0.69 mg/kg、2.23 mg/kg、1.69 mg/kg.With high molecular weightPAHs(5 to 6 ring) was 70.4% of the total, lower high molecular weight PAHs(3 ring)was 31.8% of the total. From the perspective of the spatial distribution of polycyclic aromatic hydrocarbons,surface sediment pollution level in the luzhou section of the Yangtze river is greater than the yibin section.The PAHs pollution levels of the section surface sediment of each branch into the river was from big to small order Tuojiang river、Minjiang river、Nanguang river 、Changning river、Yongning river. Source analysis showed that pahs mainly comes from oil fuel combustion and oil burning of vehicles under the condition of high temperature. The average concentration of the PAH’s is 7000 ng?g-1 in Yibin to luzhou section of the Yangtze river upstream river,at high levels of pollution levels.Threshold effect shows that acenaphthylene often produce negative ecological effect, benzo [a] anthracene, benzene and [a] pyrene occasional produce negative ecological effect, indene and pyrene and benzo [1, 2, 3-CD](g, h, I) pyrene biological have been toxic side effects for sediment biological。... |
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