Analysis And Evalation Of Pollution For Typical Drainage Rivers In Tianjin

Beitang Drainage River and Dagu Drainage River are typical drainage rivers and the main receiving waters of municipal sewage for Tianjin, which have many drainage outlets along the rivers. For many years, without systematic treatment, the two drainage rivers remained many ecological and environmental problems.At the different sampling spots along the river, the pollution situations of the two drainage rivers were analysised and evaluated. The results showed that the conventional pollutants (nitrogen and phosphorus, COD) in waters are serious, and the conventional pollutants are beyond its load, so water quality belongs to bad Ⅴ type. Heavy metals pollution in sediments in which As pollution is extremely strong ecological risks and the most serious, should be given top priority to control. Through DOM analysis, we found the DOM sources of two drainage rivers were very complex. Their sources primarily came from different terrestrial imports (mainly the river drainage outlets), and microbial is complementary role.The analysis results of the spatial change showed that the drainage outlets are the main sources of pollution. Analysis of the influence of the drainage outlets to the drainage rivers shows that for the water near the drainage outlets, the farther away from the drainage outlet are, the lower the pollutant concentration is, but the situation near the drainage outlets in sediments is opposite. Sediment pollution in vertical space distribution mainly enrich above45cm in surface.In order to investigate the transformation migration rule of heavy metals in the sediment, a simulated experiment under the condition of suspension was performed in our lab. The results showed that heavy metal Cr, Cu, As, Zn were generally sharp released at the beginning, and began turning to absorption when the maximum vaue reached, and then tend to become stable state until an adsorption-release balance was reached after150h. Temperature and stirring speed have a certain impacts on migration-transferring of heavy metals.