Ecological risk assessment and distribution of potentially harmful trace elements in lake sediments of Songnen Plain, NE China.

In order to understand the distribution and the ecological risk of the potentially harmful trace elements (PHTEs) in lake sediments of Songnen Plain, northeast (NE) China, an integrated survey of PHTEs (As, Cd, Cr, Cu, Ni, Pb, Zn and Ti) was conducted in July 2015 in 11 shallow lakes adjacent to Qiqihar and Daqing. The enrichment factor (EF) and Index of geoaccumulation (I) results showed that Cd was obviously enriched in all lakes and reached the moderate pollution level. A comparison of PHTE concentrations in the lake sediments from 2005 to 2015 found the PHTEs pollution status doubled. Multivariate statistical analysis identified the heavy industries of petroleum and steel in the cities close to lakes and excessive agricultural fertilizing in the region as possible pollution sources of the PHTEs. The Håkanson index method (RI) and the sediment quality guidelines (SQGs) were used to assess the potential risk of PHTEs in sediments. The risk degree of 11 lakes had reached a medium level of potential ecological risk except for one lake which had a low potential ecological risk status. The Songnen Plain has been significantly affected by anthropogenic activities and this study provides an effective reference for the environmental protection and management of lakes (heavy metal pollution and control) around the heavy industrial cities of China and the world.