HEAVY METAL POLLUTION ASSESSMENT AND POLLUTANTS RELEASE CHARACTERISTICS OF SEDIMENTS UNDER DIFFERENT DREDGING CONDITIONS.

To explore the possible impact of river sediments on the endogenous pollution of water body under different dredging conditions, sediments in the Luling and Guanzui sections of Tuo River were selected as research object. On the basis of pollution assessment of typical heavy metals (i.e. Cd, Cr, Cu, Ni, Pb, Zn), the release characteristics of chemical oxygen demand (COD_Cr), total phosphorus (TP) and fluoride (F) in these two sediments were studied using an indoor disturbance test device. Results show that sediments of the Luling and Guanzui sections were unpolluted to moderately polluted by Cd and Cu. The comprehensive ecological risk of the selected heavy metals in the Luling and Guanzui sediments was low. However, the single potential ecological risk of Cd was at moderate risk level. Pollution level of heavy metals in Guanzui sediment is higher than that in Luling sediment. Owing to the influences of mineral composition, content of pollutants and chemical species of pollutants in sediments, COD_Cr, TP and F in the sediments of the two sections show different release characteristics. The Guanzui and Luling sediments showed release 'source' characteristics for COD_Cr and F, respectively, to overlying water. COD_Cr and F were the priority pollutants of endogenous pollution in the Guanzui and Luling sections, respectively, of Tuo River. [ABSTRACT FROM AUTHOR]