Characteristics of particle size and biogeographic relations with ecological risk of heavy metal pollution in Beijing River sediments

Importance of the work and objectives The water environment problem of urban river is becoming more and more serious. To evaluate the ecological integrity of urban river, the surface sediments were collected from Liangshui... [ view full abstract ]

Importance of the work and objectives
The water environment problem of urban river is becoming more and more serious. To evaluate the ecological integrity of urban river, the surface sediments were collected from Liangshui River to study the physical properties of sediments and pollution characteristics of heavy metals.
Materials and Methods
In proceeding with the research, we applied Laser particle size analyzer to analyze the particle grain and BCR methodology to analyze the speciation of heavy metals: Cr, Cd, Cu, As and Zn. The relationships between the river sediments’ grain sizes and form of heavy metals, as well as the influences of the river dams have on sediment grain sizes.
Results and Conclusion
The results showed that the average particle size of sediment decreased along the flow of the Liangshui River or through dam and gate. The content of speciation of heavy metals in Liangshui River sediments followed the order: residual＞＞ oxidizable ＞ acid soluble＞ reducible. The potential ecological risk index showed that heavy metals pollution risk was relatively high in the river（RI=396.952 on average）. EF values revealed that there are anthropogenic Cd sources in the upstream and midstream of Liangshui River. River dams have the influences on the heavy metal forms. In addition, when the grain size is less than 0.2mm, the contents of non-steady-state of heavy metals increased with the particle sizes decreasing.