[Contaminative conditions evaluation of sixteen main rivers flowing into sea around Bohai Sea, in summer of 2005].

In order to study the pollution conditions of sixteen main rivers around Bohai Sea such as Yellow River and so on, water samples were collected synchronously from July 1 to July 5 in summer of 2005. The results show that, thirteen rivers are worse than the IV water, and eight rivers such as Ziyaxinhe River and so on are worse than the V water. By analysing the sharing ratio of pollution, the key pollutant is petroleum (eleven rivers), the second is nutrients, and the third is permanganate index. The comprehensive trophic state index was assessed, and it is shown that seven rivers such as Liaohe River, Yellow River and so on are eutrophic, and the other seven rivers such as Xiaoqinghe River and Jiyunhe River and so on are extreme-eutrophic. As a result, the eutrophic comditions of rivers around Bohai Sea are very serious. The organic pollutant investigation indicates that the average concentration of TOC in sixteen rivers is 16.41 mg/L, the average permanganate index is 6.04 mg/L, and the average weight percentage of the easily degradable organics in total is only 15.61%, which suggests that the organic pollution conditions of the sixteen rivers are far serious, but the fluxes of total organic matters, which are more, should be put more attention on.