Accumulation and Potential Ecological Risk of Heavy Metals in the Sediments of Rivers System in Beijing-Tianjin Area

Human activities cause heavy metals to enter the water body and consequently deposit in sediment with slow flow velocity, however little studies have explored the spatial distribution and ecological risk of heavy metals in sediments. The risk, spatial distribution and toxicity of heavy metals in sediment were investigated along the North Canal in the Beijing-Tianjin area. The study revealed that the mean concentrations of heavy metals in sediments exhibited a descending order of Zn > Cr > As > Cu > Pb > Ni > Co > Cd. The average geoaccumulation index (Igeo) value of Cd was highest and ranged from 0.2 to 2.91. Moreover, the greatest contamination of Cd (the Igeo values > 2) was observed in three sampling sites around the Tianjin City. The pollution load index (PLI) of all sampling points were greater than 1, which indicated the inflow of heavy metals originated from anthropogenic sources. The risk index (RI) values of three sampling points were greater than 300, which demonstreated high potential ecological risk. With regards to the toxicity assessment of combined heavy metals, there were two probable effect concentration (PEC) quotient (Qm-PEC) values greater than 0.5 which suggested potential toxicity to certain sediment-dwelling organisms. Identification of the possible sources and factors contributing to the content and spatial distribution of heavy metals could assist in improvement of the water quality, as well as support efficient management strategies to restoration of the environment.