| As the third River in our country, the Huaihe River plays a very enormous role in the development of national economy because of its important geographical location and richness in natural resources.Located in the intermediate zone of East China, Huaihe River is an important production areas of gain, cotton, oil and freshwater fishery, and all together a main energy resources base for north China and mid-China. Nevertheless, the water pollution has appeared since the 1970s, and then the water pollution mounted up in the 80s. In the 90s, the water pollution problems have become more acute.The water pollution has produced a serious effect on the development and utilization of water resources, and aslo resulted in the shortage of water resources, which increased the contradictons between supplis and demands for water resuorces. The water polltion has proved to be a major factor on promoting economic growth in Huaihe River basin. The water pollution situation of Huaihe River has absorbed high attention of the government, and a lot of financial power and material resources were spent in order to control the water pollution.In spite of ten years of hard work, the water pollution treatment has been at an advanced stage, but it still fails to meet the expectations of the government and the people.At the present, the water pollution in Huaihe River still remains quite serious. This paper selected the areas of Bengbu and Huainan as objectives, which belong to Anhui Provincial. The two cities of Bengbu and Huainan, located next to the middle reaches of Huaihe River, have developed heavy chemical industries and mining industries. A lot of persistent organic pollutants (POPs) were discharged into surroundings from the manufacturing process of industries and human life, which can have an important impact on the aquatic environments and aquatic ecosystems in the middle and low reaches of Huaihe River. As a typical representation of persistent organic pollutants, polynuclear aromatic hydrocarbons (PAHs) have bioconcentration, oftoxication, teratogenesis and carcinogen potential, and can be accumulated in animals and human beings through food chain, which maybe do serious danger to human health. As a result, they have been paid more and more attention to and become a most important environmental monitoring object and treatment target from a source.The paper specially researched on the law of stable organic carbon isotopes of polynuclear aromatic hydrocarbons in sediment samples to discuss the origin of polynuclear aromatic hydrocarbons in the middle and low reaches of Huaihe River. It is the first time in the Huaihe River basin to apply this method to study sources analysis, and it can provide scientific basis for source control. Ten sampling sections were set up in the middle and low reaches of Huaihe River, and water samples, suspended substance samples and sediment samples were respectively collected in October 2008.Correspondently, the water samples and suspended substance samples were obtained through filtering, and the water samples extracted by liquid-liquid extraction (LLE). Accompanied with sediment samples, the suspended substance samples were extracted by soxhlet extraction (SE). And then all of the environmental samples cleaned up by sodium sulfate solution coupled with the columns of solid phase extraction, and finally determined by high performance liquid chromatography (HPLC) for content. Moreover, another sediment samples must be treated with hydrochloric acidwith the purpose of removing inorganic carbon before they were extracted by soxhlet extraction and enriched by silica gel column chromatography, and then the organic carbon stable isotopes were determined by gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS).The research results showed as follows:1. The total polynuclear aromatic hydrocarbons concentrations in the water samples,suspended substance samples and sediment samples ranged within little difference, and the total polynuclear aromatic hydrocarbons concentrations in water samples from ZhengYangguan spot were the most, as well as that of suspended substance samples and sediment samples from BengBuZha spot. At the same time, the total polynuclear aromatic hydrocarbons concentrations of all the environment samples reflect the phenomenon that the sediment samples were the most among the three,and the suspended substance samples took second place,and the water samples were least.2. As far as different ringed PAHs distribution in all environment samples is concerned, the low ring polynuclear aromatic hydrocarbons in water samples were not discovered, and the high ring polynuclear aromatic hydrocarbons were determined with low level. On the other hand, the low ring polynuclear aromatic hydrocarbons in suspended substance samples were superior in numbers, and the high ring polynuclear aromatic hydrocarbons in sediment samples from PingWei spot, WuXiaoJie spot, WuHe spot, FuShanJi spot, LiuXiangXiang spot gave priority to the low ring polynuclear aromatic hydrocarbons, however, it was the opposite in other sampling spots.3.Based on the ecological risk assessment on polynuclear aromatic hydrocarbons in water samples, the monomer of Benzo(a)pyrenene, Dibenzo(a,h)anthracene and Indeno (1,2,3-cd) pyre would bring potential ecological risk to the healthness and safety of the people along the rivers, so some relative policies and measures need to be adopted to control and reduce the risk by the department concerned.4.Compared with the ecological risk assessment on polynuclear aromatic hydrocarbons in sediment samples, the monomer of Acenaphthene, Fluorene, Dibenzo(a, h)anthracene were more likely to reveale negative biologic effects, and the probability of ecological risk on the middle and low reaches of Huaihe River was from 10% to 50%. The same applied to the monomer of Acenaphthylene to ZhengYangGuan spot and BengBuZha spot, while other polynuclear aromatic hydrocarbons post a low risk5. A preliminary discussion on the polynuclear aromatic hydrocarbons source in sediments from the middle and low reaches of Huaihe River was given with the aid of stable organic carbon isotopes analysis. The results indicated that polynuclear aromatic hydrocarbons in sediments from the middle and low reaches of Huaihe River were mainly derived from coal combustion, thus some appropriate measures should be taken to control the generation, emission and purificationof polynuclear aromatic hydrocarbons in terms of their sources, such as chosing the appropriate coal-burning boiler, improveing the gas-smoke retrieving equipment and installating the new dust separator, which could stop and reduce the polynuclear aromatic hydrocarbons into surroundings.
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