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Suspended particulate matter (SPM) is a major contamination source in urban rivers. In this work, the Beiyun River, northern China, was used as a case study to determine the characteristics of heavy metal spatial distribution in SPM, and to evaluate the potential ecological risks and identify heavy metal sources. The concentration of seven heavy metals and associated indicators (TC, TN, TP, and OM) were measured at 12 sites and analyzed by Pearson correlation (PC) and principal component analyses (PCA). The average concentrations of Cr, Ni, Cu, Zn, As, Cd, and Pb were 70.72, 27.88, 31.35, 115.70, 27.77, 0.23, and 29.62 mg/kg, respectively, and significant spatial differences occurred between some elements. Igeo values indicated the ranking of heavy metal pollution in SPM as As > Cd > Zn > Cu > Pb > Cr > Ni. The Eir analysis demonstrated that the order of potential ecological risk of the seven metals was Cd > As > Cu > Pb > Ni > Cr > Zn. RI (potential ecological risk index) results confirmed high potential ecological risk in objective area. Of the measured heavy metals, Cd represented the highest pollution risk. Significant positive correlations were found between TC, TN, TP, and Cu. Three element pairs, Zn-Cd, Cr-Cu, and Cr-Ni, had strong correlations. Zn, Cu, and Ni were mainly introduced by human activities, and Cr was mainly from natural processes. This information on the concentration, risk, and sources of SPM in Beiyun River provides an important reference for reducing heavy metal pollution in SPM of a typical river in the Haihe River Basin.

The objective of this study was to investigate the salinisation characteristics of a semi-arid river network in northern China and highlight the influencing factors and risks. The Ziya River Basin, a typical semi-arid river network located in the North China Plain, is studied herein. Overlying water, surface sediment and riparian soil samples were collected in July and December of 2014 in the Ziya River Basin. The results showed that the average concentrations of salt content in the overlying water and surface sediment of 10 rivers in the Ziya River Basin were 1105.64 and 2159.35 mg/L, respectively. High level of salinisation was found in most rivers not only in overlying water, but also in surface sediment. The impact of the salinisation of overlying water on riparian soil diminished with distance away from the shore and had no impact beyond 15 m from the shore. Heavy pollution can contribute greatly to the salinisation of the water column and can cause significant impacts on river sediment and riparian soil. Salinisation in the overlying water affects the sediment and riparian soil, and reveals that the high risk of salinisation in the Ziya River Basin has been underestimated.